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A SYSTEM 
OF PSYCHOLOGY 



A SYSTEM 
OF PSYCHOLOGY 



BY 



KNIGHT DUNLAP 

ASSOCIATE PROFESSOR OF PSYCHOLOGY IN THE 
JOHNS HOPKINS UNIVERSITY 



NEW YORK 

CHARLES SCRIBNER'S SONS 

1912 






Copyright, 1912, by 
CHARLES SCRIBNER'S SONS 




eCI.A309474 



/ 



TO 

ELMER ELLSWORTH BROWN 

IN ACKNOWLEDGMENT OP WHAT I OWE TO HIS 
TEACHING AND FRIENDSHIP 



PREFACE 

I SHOULD not be willing to add to the large num- 
ber of psychology texts already in existence did I 
not believe that this book, in spite of its faults of 
omission and commission, possesses certain good 
points not found in the other English texts of re- 
cent date. 

My greatest effort has been to present as consist- 
ent and systematic a sketch as possible of the general 
field of normal human psychology, elaborating the 
details only when they are essential to the general 
survey. In a field which is in great and increasing 
danger of becoming unsystematized to the point of 
chaos, even to the trained specialist, this method 
of introduction is absolutely essential. 

I have tried to show that the data of psychology 
cannot at present be definitely described except in 
terms of theories which are more or less ^^philosoph- 
ical,^^ and that the attempt to divorce the data from 
the theories would result in the uncritical acceptance 
of fragments of theories. It is important that the 
student should grasp this truth in the beginning, 



Vlll PREFACE 

and not be taught a pseudo-final system of facts 
which later must crumble cataclysmically when he 
takes a new point of view. 

I have not attempted to write a book so simple 
that the student might read and understand it 
without effort: rather, I have endeavored to write 
that which should demand and reward hard study. 
The book is not designed to be made the sole basis 
of a course in elementary psychology. It ought to 
be accompanied by lectures prepared by a com- 
petent teacher, having special reference to the 
difficulties and lacunae of the text, and to its dif- 
ferences from the psychological theories held by 
the teacher. Certainly, the book cannot be used as 
a text from which both students and teacher may 
draw their information. As a main or supplement- 
ary text for semiadvanced students, it should find 
its greatest usefulness. 

The only originality I can claim is in the way in 
which I have worked up materials borrowed from 
many places. I have not given credit for my bor- 
rowings, because in many cases the sources are too 
obvious to be mentioned, and in other cases what 
has been borrowed has been so distorted in the proc- 
ess that the individual to whom I am indebted 
might resent the ascription if credit were given. 



PREFACE IX 

The chief influences which have shaped my psy- 
chological constructions have come from the writ- 
ings of James and from my contact, as a pupil, first 
with Howison, later with Stratton, and finally with 
Miinsterberg. 



CONTENTS 

CHAPTER PAGE 

I. Introduction: 

1. The Meaning of Psychology .... 1 

2. Terminology 5 

3. Extrinsic Helps 8 

II. Preliminary Analysis of Content: 

1. Complexity of Content and Complexity 

of Experience 12 

2. General Classification of Elements of 

Content 13 

3. Terminology 16 

III. Sensation in General: 

1. Sensation, Physical Stimulus, and Physi- 

ological Process 18 

2. Matter and Psycho-Physical Causation . 25 

3. The Lag of Sensation 27 

4. Secondary Sensations 31 

5. The Characters of Sensation .... 32 

IV. Sensation-Quality : 

1. General Classification 38 

2. Sensation and Brain Process .... 43 

3. Sensations of Taste ....... 44 

4. Sensations of Smell 49 

5. Visual Sensations 54 

6. The Schematic Representation of Visual 

Qualities 56 

7. Achromopsia and Parachromopsia . . 67 

8. Color Adaptation and Contrast ... 74 

9. Auditory Sensations 80 

10. Cutaneous and Subcutaneous Sensations 84 

11. Kinsesthetic and Coensesthetic Sensations 95 

xi 



Xll CONTENTS 

CHAPTER PAGE 

V. Thresholds of Consciousness .... 

1. Stimulus-Thresholds 101 

2. Stimulus Difference Thresholds . . . 105 

3. Other Thresholds 106 

4. The Constant Error 106 

VI. Sensation-Intensity: 

1. Intensity of Sensation and Intensity of 

Stimulus 109 

2. Weber's LaW Ill 

3. The Comparison of Intensity-Differences 114 

4. The Relativity of Sensation .... 116 

5. Beats 118 

VII. Protensity and Extensity of Sensation: 

1. The Duration-Quality 120 

2. Extensity 122 

3. Overtones and the Musical Scale . . . 125 

4. Timbre 132 

5. Extensity and Intensity 134 

VIII. Local Significance: 

1. Localization and Local Sign . . . . 137 

2. The Discrimination of Local-Sign Differ- 

ences . 139 

3. Local Sign in Auditory Sensation. . . 143 

4. Olfactory Local Sign 145 

IX. Relational Elements in the Content of 
Consciousness: 

1. General 146 

2. Platonic Ideas and Matter 149 

3. Intellect 150 

4. The Reality of Relational Content . . 151 

X. Images as Elements of Content: 

1. Imagination and "Image Types". . . 153 

2. The Function of Imagination .... 160 



CONTENTS Xlll 

CHAPTER PAGE 

XI. Retention, Memory, and Recall: 

1. Retention 169 

2. Memory 174 

3. Recall 177 

XII. Association: 

1. The Principles of Association .... 180 

2. Voluntary Recall 192 

3. The Probable Physiological Basis of 

Association 194 

XIII. Perception: 

1. The General Nature of the Content in 

Perception 196 

2. Perception, Illusion, and Hallucination . 201 

3. The Determination of Perceptual Truth 

and Falsity 205 

4. The Causes of Illusion 208 

5. Space Perception 212 

6. The Perception of Things 227 

7. The Perception of Time 229 

XIV. Affective Content, or Feeling: 

1. Affection and Cognition ...... 242 

2. Pleasure and Pain 244 

3. Conation and Interest 250 

4. Emotion 255 

5. The Ccensesthetic Factor in Emotion . . 259 

6. The Cognitive Factor in Emotion . . 261 

7. The Classification of the Emotions . . 263 

XV. Action and Will: 

1. Action in General 265 

2. Volition 270 

3. Volition as Activity 273 

4. Automatic Action 274 

5. Instinctive Action and Learning . . . 277 

6. Habit 281 



XIV 



CONTENTS 



CHAPTER PAGE 

XVI. The Self, or Empirical Ego 285 

XVII. The Degrees of Consciousness: 

1. Consciousness, Attention, and Vividness . 292 

2. Vividness and Intensity 295 

3. Factors Determining Vividness . . . 298 

4. Attention and Interest 301 

5. Vividness and Practical Advantage . . 302 

6. Judgment 303 

7. The Scope of Attention 304 

XVIII. The Time Relations of Consciousness: 

1. Presentation and Image 306 

2. Rhythm 309 

3. Duration of Attention to Continuously 

Presented Sensation 313 

4. The Fluctuations of Minimal Sensations 316 

5. The Selective Fluctuation of Vividness . 318 

6. The Conditions of Constant Attention . 323 

XIX. The Subconscious: 

1. The Lower Limit of Vividness . . . 325 

2. What the Subconscious is Not .... 326 

3. The Two Sorts of Marginal Consciousness 328 

4. Multiple Personality 331 

XX. The Ego 336 

XXL The Occult: 

1. The Study of the Occult 342 

2. Telepathy 343 

3. Mysticism 348 

4. Spiritualism and Mediumship .... 350 

References . .' 355 

Index 363 



A SYSTEM 
OF PSYCHOLOGY 



A SYSTEM 
OF PSYCHOLOGY 



CHAPTER I 

INTRODUCTION 
I. The Meaning of Psychology 

It is much easier to tell the beginner what psy- 
chology is not than it is to tell him what psychology 
is. Just as it would be impossible to give an in- 
teUigible definition of mathematics to a person un- 
familiar with the elementary principles of number- 
relations, so it is impossible to make clear to the 
average student the nature of psychology when he 
is just beginning to study it. In order that one 
may have a definite idea of what psychology is, he 
must know some psychology; and a person who 
has not studied the subject under competent guid- 
ance is not apt to know any psychology in the strict 
sense. It is true, on the one hand, that there is a 
great deal of information which is popularly called 
psychological; and, on the other hand, that every 



2 A SYSTEM OF PSYCHOLOGY 

person knows much that is really psychology, al- 
though the persons in question do not realize that 
it is such. These two species of misunderstanding 
contribute to the difficulty of the task when one 
commences to study the subject scientifically. It 
is clear, therefore, that what we say now in a general 
way concerning psychology should be brief, and 
that the meaning thereof will probably be clear to 
the student only as he reverts to it after completing 
the volume. 

We may commence advantageously by warning 
the student against some of the more common 
misconceptions of psychology. In the first place, 
while on the one hand psychology is not the " study 
of the soul,'' on the other hand it is not "soulless'' 
in the sense of doing away with a soul. It is a com- 
monplace that \jrvxo\oy{a is not to be taken in its 
literal significance as the name of our field of labor, 
and that a considerable portion of the psychologi- 
cal discussion gets along without any mention 
of any sort of "soul." But in a comprehensive 
analysis it is not possible to avoid reference to 
something which may properly be called a "soul," 
although it is by no means the "psyche" of the 
Greeks and of the current popular conception, and 
although it is impossible really to study it. 



INTRODUCTION 6 

In the second place, psychology deals very little 
with the so-called "occult"; with telepathy, clair- 
voyance, and the other charlatanisms which are 
often so successfully employed in separating the 
fool from his money. Yet if we do not affirm, 
neither do we deny, that there may be, at the core 
of some of these concretions of humbuggery, cer- 
tain elements of psychological interest and impor- 
tance. The investigation of such matters belongs, 
however, not properly to psychology, but to ^'psy- 
chic research." ^ 

In the third place, the term "psychological" in 
current popular usage designates a certain delicacy 
or niceness of discrimination or adjustment. Thus 
the "psychological moment" implies an instant of 
time so appropriate for a certain act that a moment 
before would be too early, and a moment after too 
late. Any very precise analysis or description, 
of the characteristics and activities of human be- 
ings; or even a simulation of precision, is called 
"psychological"; and hence we find mention of 
"psychological" novels, and so forth. Now while 
psychology modestly acknowledges the pretension to 

^The terms "psychic'^ and "psychical" must be distin- 
guished carefully from "psychological." It is to be regretted 
that either of the first two terms is ever applied to the data 
which we study in the name of psychology. 



4 A SYSTEM OF PSYCHOLOGY 

exactness of analysis, she must deny any exclusive 
claim thereto, and cannot even pose as the only 
science which analyzes human activity and ex- 
perience. In this popular sense of the term, physi- 
ology, logic, and ethics are, if anything, more " psy- 
chological'' than is psychology. 

Finally, psychology is not the study of the func- 
tions of the nervous system. In fact, all the essen- 
tial points of psychology can be expounded, as they 
have been developed, without reference to the ner- 
vous system, or by reference to a conception thereof 
which is ridiculously inaccurate. Nevertheless, it 
is true that psychological principles and facts are 
more easily described and investigated when re- 
ferred to the structure and probable activity of the 
brain and nerves, as understood by the person to 
whom described or by whom investigated, and we 
believe that the more closely the physiological con- 
ceptions approach agreement with the actual facts of 
structure and function, the more facile the progress 
of psychology. 

As for a positive definition we may give the fol- 
lowing, which will be made clear by the further 
discussion: psychology is the study of experience; 
of the reference of experience to its content; of any 
direct reference which it may have to a subject of 



INTRODUCTION O 

experience; and of the content of experience in so 
far as it is directly related to experience. 

2. Terminology 

The terms used in this book may at first be 
a series of stumbling-blocks. Not only will the 
meaning in which many of them are used be found 
to differ decidedly from the meaning attached to 
them in every-day language, but in many cases the 
terms are not used in the senses in which thev are 
used in other books which will be read by the stu- 
dent. This confusion is unavoidable. The terms 
have been used in so many different sciences (to say 
nothing of their unscientific uses), that they have 
acquired a variety of meanings, and we are obliged 
to select the significations which seem most appro- 
priate. Some words, such as "mind,^' "intelli- 
gence," and "soul," have had, and still have, so 
many different meanings that they have come at last 
to mean practically nothing, and we hesitate to use 
them at all where accuracv is essential. In the 
choice of the signification to be given to a term we 
should be guided not only by predominance of 
present usage amongst psychologists, but also 
by the historical setting of words, and by popular 
usage; and having attached a given signification to 



6 A SYSTEM OF PSYCHOLOGY 

a term we ought to endeavor to adhere to it through- 
out. 

The term ^* experienced^ is currently used in two 
ways. In the first place, it means to know, appre- 
hend, or perceive something; as when I say I ex- 
perience a sound, a color, a pain, or an emotion. 
In the second place, it means that which is appre- 
hended or directly known, that is, the sound which 
is heard, the emotion which is felt, etc., are called 
experiences, or kinds of experience. There has 
been a great deal of shifting back and forth from the 
one of these meanings to the other, which has in- 
troduced deplorable confusion; and, manifestly, if 
we wish to avoid such trouble we must adopt and 
cling to one meaning. We shall, therefore, use the 
term in the first sense given above; to designate the 
being aware of something, and not that of which 
one is aware (except in so far as one may possibly 
be aware of being aware, which need not concern 
us here and now). This first meaning is, after all, 
the fundamental one, and we could hardly avoid 
using the term in this way even if we used it also 
in the other. 

The noun "experienced^ is equivalent to the word 
" consciousness,'' and we shall so use it, and shall use 
the verb ^^tobe conscious of as equivalent to "to 



INTRODUCTION 7 

experience/' *' Consciousness '^ meant originally 
"the knowing that one knows/' "the experiencing 
that one experiences/' to which we above referred 
parenthetically; but it has completely lost in mod- 
ern psychological usage that former restriction of 
meaning. It is, however, used frequently in the 
sense which we have given as the second meaning 
of experience, namely: that which is apprehended 
or known directly. Some authors with due notice 
use the term in both senses, and others, we regret to 
say, make similar usage without notification. Out- 
side of psychology the historical meaning is still 
in vogue to some extent, and the resulting misunder- 
standing may be readily conceived. 

"Knowledge" is a wider term than "experience" 
or " consciousness," and our use of the former term 
in defining the other two must be understood with 
this qualification. It is only direct knowledge as 
distinguished from indirect, that can be identified 
as experience. The significance of this distinction 
will become clearer later. 

For that which we experience, or of which we are 
conscious, we have the convenient and unambig- 
uous term "content of consciousness'^ or "content 
of experience." Frequently, however, we speak of 
the "objects" of consciousness or experience, or of 



8 A SYSTEM OF PSYCHOLOGY 

^* psychological objects/' Thus, the sound which I 
hear is a psychological object, as distinguished from 
the air vibrations which cause it, which latter are 
physical objects, and, as we shall see, are not 
heard or experienced, although we may know of 
them. 

Other terms will be defined and explained in the 
sections in which their comprehension can be made 
most easy. 

3. Extrinsic Helps 

The proper preparation for the study of psychol- 
ogy cannot be prescribed in a way that will cover 
the needs of diverse individuals. One student will 
make excellent progress while lacking certain ad- 
vantages without which another sticks fast. The 
elements of physics and of anatomy ought to be 
understood, and the cell-physiology which is given 
in the thorough courses in elementary biology or 
physiology is of value. The student will get all 
he needs of these subjects from good lecture and 
demonstration courses in them, and, if after his 
elementary course in psychology he decides to follow 
it farther in some particular direction, he will then 
discover in which of the sciences he needs laboratory 
training. Perhaps the greatest need for the be- 



INTRODUCTION 9 

ginner is an adequate training in literature, which 
may be acquired by well-directed reading; for 
psychology is least of all the subject in which any- 
thing can be communicated or comprehended in a 
special jargon or terminology, but requires all the 
assistance that can be given by command of the re- 
sources of the language of the masters in letters and 
of the speech of the plainer men. After literary 
training we should rank in importance a knowledge 
of physics as a close second. 

We have omitted the customary anatomical pict- 
ures and discussions from this book, as the result 
of deliberation and conviction. Cuts of the brain 
and nervous system are readily accessible to any 
student who cares to look at them, and it is better 
for him to be sent to good anatomies to consult a 
hundred pictures than to have a dozen or so chosen 
out and put before him. Each instructor, more- 
over, has his own choices of preparations, models, 
charts, slides, and cuts, and of methods of presen- 
tation of nervous anatomy and histology. A super- 
ficial presentation here (and none other could be 
given in the limits of this book) would be a posi- 
tive detriment. The books and cuts suggested are 
merely first aid to the student working alone. 

Piersol's Human Anatomy; Howell's Text-Book 



10 A SYSTEM OF PSYCHOLOGY 

of Physiology; Quain^s Anatomy^ vol. I, pt. II, and 
vol. II, pts. II and III; Schafer's Text-Book of 
Physiology, vol. II, and McKendrick and Snod- 
grass's Physiology of the Senses are all valuable 
aids in understanding the schematic anatomy of 
the nervous system. Excellent plates of brain, eye, 
and ear are given in the Sorbotta McMurrich Atlas 
and Text-Book of Human Anatomy, vol. III. We 
will give references chiefly to Piersol and Quain, 
because one of these will doubtless be accessible to 
the student. No specific references will be given 
to McKendrick and Snodgrass because the book is 
small, and appropriate material easy to find therein. 

As for the general principles of nervous function, 
the best brief account is found in Howell, chaps. 
VI to XI, inclusive. The account of the nervous 
system given in Piersol, beginning on page 996, is 
especially valuable. For the needs of students of 
psychology, however. Part First of Ladd and Wood- 
worth's Elements of Physiological Psychology is 
without doubt the best available general treatise on 
the structure and functions of the nervous system. 

On the physical problems of light and sound, 
the articles by Lewis and Hallock, respectively, in 

^ The references are to the tenth edition of Quain, and 
third edition of Howell. 



INTRODUCTION 11 

Duff's Text-Book of Physics, will be found element- 
ary and useful. Zahm's Sound and Music is an 
intelligible and interesting treatise on acoustics. 
Unfortunately, the more commendable treatises, 
such as Barton's TexUBook on Sound, are too tech- 
nical for the student who is not a specialist in phys- 
ics. TyndalFs Lectures on Sound are still useful, 
and Helmholtz's Sensations of Tone (Ellis's trans- 
lation) is the starting-point for the student inter- 
ested in the psychology of audition. 



CHAPTER II 

PRELIMINARY ANALYSIS OF CONTENT 
I. Complexity of Content and Complexity of Experience 

The content of your experience at any given 
moment in your life history is exceedingly complex. 
As you sit reading this book you have visual im- 
pressions of various forms and colors from the book 
and from surrounding objects; you get various 
sounds; odors; impressions of touch from the book 
and from your clothing and chair; feelings in the 
muscles, joints, eye-sockets, and viscera. All these 
things are sensed or perceived, and simultaneously 
something is thought of; e, g., the meaning of this 
print is presented as a content of thought. Add to 
these factors the emotional complexes of interest, 
weariness, hunger, satisfaction, disgust, annoyance, 
or whatever else is giving "tone" to your content, 
and you begin to see the truth of the opening sen- 
tence in this paragraph. 

Although the content of experience is demonstra- 
bly composed of a multitude of parts or elements 

in complicated organic interrelation, it does not fol* 

12 



PRELIMINARY ANALYSIS OF CONTENT 13 

low that experience itself is complex. This has been 
a stumbling-block for modern psychology because 
of the frequent lack of clear distinction between 
consciousness and its object. It is often said that 
the content is not complex, but is simple and uni- 
tary; and that the elements into which we apparently 
resolve it by analysis are really new content brought 
into existence by our analysis. In stricter language, 
this really means that while the content which you 
apprehend is complex, and may be resolved into its 
elements, the apprehension or experience of the 
content is not itself a complex made up of the appre- 
hensions of the different elements. To this dogma 
there is so far no reasonable objection, although it 
may be found ultimately that even experience is 
not so unitary as it appears to be; or rather, as it 
suits our presuppositions to think it is. 

2. General Classification of Elements of Content 
In the examination of content of consciousness it 
is important to ascertain as definitely as possible 
how many sorts of elementary content there are. 
By elementary content, or element of content, we 
mean that portion of content which is not itself com- 
plex; that is, which cannot in turn be analyzed into 
component parts. Of such elements there appear 



14 A SYSTEM OF PSYCHOLOGY 

to be four groups, each including a number of sub- 
groups. Further investigation may show that at 
least one of these groups must be fundamentally 
revised, and perhaps eliminated, but we must give 
them all consideration. These four kinds of con- 
tent are sensations, relations, feelings, and images. 
We will indicate briefly in the next paragraphs what 
these terms cover. 

Sensations are such things as color, sound, odor, 
and warmth. Look at a drop of red ink on a paper 
before you; the color — the red — abstracted from 
its position on the paper, from its reference to other 
objects, from its familiarity, from its likeness or 
unlikeness to other colors; in short, from every- 
thing but the color as presented, is a sensation. So 
the sweet from sugar on the tongue, abstracted from 
all the attendant impressions in the mouth, from 
the fact that it is sugar, from the pleasantness, etc., 
is a sensation. 

It is one of the commonplaces of psychology that 
a sensation is never presented alone to your ex- 
perience. Neither is a mere group or complex of 
sensations ever presented alone to the adult, and 
probably not to the infant. Always there are 
other elements, such as difference, familiarity, un- 
pleasantness, etc., joined with it. Nevertheless, 



PRELIMINARY ANALYSIS OF CONTENT 15 

we can pick out from among the mingled factors 
of the complex the sensation itself and consider it 
in detail. 

Relations are easily recognized, or at least some 
of them are. Similarity, difference, sequence, inter- 
mediacy, possession, etc., are experienced just as 
directly as are sensations. Perhaps the instances 
given are not simple; perhaps they may be analyz- 
able into simpler relations, but they are sufficiently 
good specimens. 

Feelings are most easily identified in emotions 
or passions. Joy, sympathy, ennui, rage, hunger, 
pleasure, are contents which involve complexes of 
bodily sensations, relations, and in addition the 
feelings which are their most important character- 
istics. The total complexes named may all with 
fairness be called emotions, and their analysis pre- 
sents probably the maximum of difficulty with which 
psychology has to contend. But it is reasonable to 
conclude for the present that they cannot be com- 
pletely accounted for without taking into account 
elements of feeling. If it should eventually be 
demonstrated that these feelings are nothing but 
specific sensations, we will have neither done nor 
suffered harm by listing them as elements or quasi- 
elements. 



16 A SYSTEM OF PSYCHOLOGY 

Images are generally considered as being the 
"copies" or "revivals" of sensations and of com- 
plexes of sensations previously experienced. Hav- 
ing been conscious of the sensation of red under the 
influence of physical light-waves you may later ex- 
perience an "image" which is in some respects like 
the sensation, and which will represent it. By the 
images of sound, color, touch, and of sensations from 
the muscles, we are enabled to "think" of content 
which is not present; this is practically the doctrine 
as Aristotle handed it down, and it is the doctrine of 
current psychology. 

We regret the necessity of departing radically 
from established opinion, but feel the obligation to 
warn our readers at once of our conclusion that the 
belief in the existence of such forms of content is a 
delusion, flowing partly from certain peculiarities of 
consciousness and partly from metaphysical preju- 
dices. We shall present the case in detail in the 
proper place, not slighting the current theory. 

3. Terminology 
In contradistinction to content imagined, we speak 
of content inhtited or apprehendedy and oppose in- 
tuition or apprehension to imagination. Thus, 
when light-rays fall upon my retina, I intuit a light 



PRELIMINARY ANALYSIS OF CONTENT 17 

sensation. Sometimes the sensation is said to be 
present as opposed to a sensation or other content 
merely imagined. Perception appHes to intuition, 
and to intuition plus imagination; usually it has 
the latter reference. This will be clear to the reader 
after he has studied the chapter on perception. 
Intuition is popularly used to signify an occult or 
inexplicable awareness of some fact; it is needless 
to say that as we use the word it has no shred of 
that meaning, which is a perversion of the correct 
signification. 



CHAPTER III 

SENSATION IN GENERAL 

I. Sensation, Physical Stimulus, and Physiological 

Process 

Sensation — that which is experienced through 
the senses, or through sense — must be distinguished 
rigidly from the physical stimulus, on the one hand, 
and the nervous activity which is caused by this 
stimulus, on the other hand. The normal stimulus 
is some activity of what we call "matter,'' usually 
outside of, but acting on, the body of the individual. 
Thus, the oscillation of the air particles which act 
on the inner organs of the ear and produce sound; 
the vibration of the ether which stimulates the ret- 
ina of the eye and occasions the experience of light; 
the chemical activity of substances, which produces 
odor; these are instances of stimuli. There is little 
difficulty in distinguishing stimuli from sensations, 
even for the beginner, for a little reflection convinces 
us that these physical facts are not experienced, 
but only inferred. WTien, for instance, I hear a 
tone, I am not conscious of the back-and-forth 

movement of the air particles; and when I see a 

18 



SENSATION IN GENERAL 19 

color I am not experiencing the undulations of the 
ether. In the latter case the stimulus is so far from 
being experienced that it has required great labor 
to discover its real nature (assuming that we do 
know it now) by inferences from observations, and 
it took years for those who held the present theory 
to convince of error those who drew different con- 
clusions from the observations. Even to-day phys- 
icists do not profess to have a complete under- 
standing of the actual behavior of the ether and 
some of them doubt its existence. Yet an ignorant 
man, who has never heard of ether, and whose views 
on the transmission of light are amusing, may ex- 
perience light and color sensations which are as 
highly developed as those of any one. The smell 
of a volatile substance depends doubtless on the 
arrangement of the atoms in the molecules (or on 
some such physico-chemical factor), but smell itself 
gives no direct information as to this arrangement. 
So it is throughout. What you experience through 
the senses is not a material object, or any part of a 
material object, although we have learned all we 
know concerning material objects from a study of 
the behavior of sensations. We have discovered dur- 
ing the last ten centuries a great deal about the phys- 
ical activities corresponding to most of our sensa- 



20 A SYSTEM OF PSYCHOLOGY 

tions, and the general principles of their behavior; 
which helps to create in the unreflective the belief 
that we experience directly the physical activities 
themselves. 

The difference between the sensation and the 
nervous process, especially that in the brain, is 
harder to grasp than is the difference between sen- 
sation and stimulus. This difficulty is at once ex- 
emplified and increased by the fact that many physi- 
ologists seem to teach that there is no difference. 

The psycho-physiological confusion is rendered 
well-nigh hopeless by the ambiguity of the term 
" nervous process/' and though the ambiguity is not 
dangerous in physiology, it is productive of much 
trouble when physiology is brought into relation 
with other studies. The terms " brain/' "nerve/^ 
etc., may mean the actually experiencible; that is, 
visible and tangible objects; and " nervous process,'' 
accordingly, may signify changes which may act- 
ually be watched, or which might be observed if 
sufficiently delicate instruments were available. On 
the other hand, the terms may signify the matter 
and material changes which are supposed to be at 
the basis of these observable things or changes, and 
which, of course, we infer, but do not experience. 
If, for example, someone could lay bare your brain 



SENSATION IN GENERAL 21 

and with proper instruments observe the operations 
of that mechanism, his sensations would be, loosely 
speaking, brain processes; at least, the brain proc- 
esses observed would be partly composed of his 
sensations. But this is not what the physiologists 
mean; they mean that your sensations, while you 
observe anything whatsoever, are identical with your 
brain processes. This meaning does not refer to 
the brain processes in the first sense mentioned, 
although often taken in that way, for no thoughtful 
person would be guilty of supposing that while, for 
instance, you are watching an indigo blue light, 
that shade of blue could be discovered by obser- 
vation of your brain cells. In general, if you could 
watch the light (or other object), and at the same 
time watch through some instrument all the changes 
observable in the brain and nerve cells, you would 
find practically nothing in common in the two ob- 
jects. 

The brain processes the physiologists mean when 
they say that a sensation is a brain process are the 
material facts and transformations which are not 
observable directly as brain facts, but which we can 
infer; in short, the things represented by the sym- 
bols of chemistry. What you see, when you ex- 
amine a nerve, are only sensations of light and color; 



22 A SYSTEM OF PSYCHOLOGY 

what you feel are touch sensations; you do not see 
or feel the matter of the nerve. The sensations 
you experience and which you may suppose to be 
the nerve under examination are really transforma- 
tions in your own material nerves, which cannot be 
experienced by anybody or anything except your 
own " mind/* or perhaps can only experience them- 
selves. Thus, the sensation, when followed relent- 
lessly back in the physiological system of events, is 
apparently found to have disappeared completely, 
and to have been replaced by something else. 

The vulgar way of accounting for this vanishing 
of . sensations under scientific scrutiny is to suppose 
that the "mind'* experiences these brain changes 
and experiences them (wrongly, indeed,) as sensa- 
tions. This is merely an unintelligent reversion to 
an older and more respectable theory — that the 
processes in the brain ^produce the sensations in the 
" mind," — which theory does not identify the process 
with the sensation. A more modern way is to say 
that the brain process experiences itself. Thus, we 
do away with the concept of "mind," except as a 
name for a certain activity of brain cells and arrive 
at a point of view which is apparently quite simple. 
But this little subterfuge saves us only for a moment, 
and either method of explanation, if consistently 



SENSATION IN GENERAL 23 

adopted and carried out, lands us either in the con- 
clusions of the Hindu Vedantists, that the world 
which we seem to experience is not real but only 
illusion; or in idealism, which holds Mind to be 
the only reality. If we wish to hold to the theory 
that there is a real world to experience, we must 
hold that sensation is not brain state nor brain ac- 
tivity. 

The student will probably ask himself — very 
likely has asked while reading this chapter — " Where 
is sensation ?^^ The commonplace answer, ^*Itis 
in the brain,^' seems to commit one to the doctrine 
of sensation as a brain state; and yet, where else 
can the sensation be? The sensation is not in the 
brain unless the whole body is in the brain. Sup- 
pose you have before you a red surface and ask your- 
self, "Where is the red?^' Put your finger on the 
surface, and the evident answer is, that it is where 
the finger is; that is, "out there,'^ in space. Of 
course, there is a possibility that you are deluded 
in both cases, and that neither the color nor the 
finger are "there,^^ but are both in the brain; or 
rather, since the brain itself is in the same class with 
the finger, the whole outfit is " in the mind." Thus, 
if you begin by assuming that the sensations are in 
the "mind," as opposed to a "real world," you will 



24 A SYSTEM OF PSYCHOLOGY 

conclude in the end that the whole knowable uni- 
verse is in the "mind/^ unless you are too busy, too 
lazy, or too dull, to carry the process you have 
started to its logical conclusion. If you are satis- 
fied, and call this mental universe " real,'^ you have 
reached idealism. If you are dissatisfied, and think 
this does not give you reality enough, you have 
reached the Hindu view of the world as Maya, or 
illusion.^ 

We do not feel either of these conclusions to be 
satisfactory, and, therefore, are forced to assume 
that sensations are not in the brain, but are where 
they are experienced as being, or are so in many 
cases. In some instances they may be at some 
other point of space, and, hence, wrongly "lo- 
cated'^; and there may indeed be in all cases a cer- 
tain amount of error in location; but error is possible 
here, as elsewhere, only if there is a basis of correct- 
ness. 

If it should be proven that what we call "out 
there ^' is really in the mind, then our analysis is 
still true, for the sensation is "out there" in so far 
as there is any " out there." This whole matter is 



^ If sensations are brain states, or "in the mind," so are all 
other experiencible elements and complexes; and we expe- 
rience nothing which is outside the brain (or mind). 



SENSATION IN GENERAL 25 

subject to many sophistical difficulties which it re- 
quires clear philosophy to dispel, but for the pres- 
ent the student need not abjure his naive common- 
sense view, which will not in any event vitiate his 
analysis, whereas the opposite view certainly would 
be risky. The illusion theory and the idealistic 
hypothesis, are not necessary for science or psy- 
chology. 

2. Matter and Psycho-Physical Causation 

Understanding that sensation is not the same 
thing as the stimulus which may physically cause 
it, and is not the same thing as the brain and nerve 
processes which may also be said to cause it, we still 
find it useful and necessary to treat of sensation 
and other mental processes in relation to both of 
these. The question of the ultimate relation of the 
mental to the material, with its more or less def- 
inite answers of "parallelism,^' " interactionism,'' 
" materialism,^' etc., will be of interest and impor- 
tance to the student as he goes deeper into psychol- 
ogy, but are so far from being essential at the start 
that a considerable knowledge of psychology is 
necessary before he can take up these matters in- 
telligently. It is at present no business of ours to 
decide whether matter actually exists as substance. 



26 A SYSTEM OF PSYCHOLOGY 

or whether it is only a convenient fiction, or whether 
it exists in the Huxleyan sense as the universally 
valid law of the content of experience. We must 
hold the concept of matter as scientifically indis- 
pensable/ at least for the present, and take it into 
consideration when dealing with the facts of experi- 
ence. The author is personally convinced of the 
correctness of Huxley^s theory, which has the weight 
of centuries of philosophy behind it; but nothing in 
the present volume should be any the less harmoni- 
ous with your postulates if you hold that matter is 
an actual thing or substance, or hold some other 
view; because none of our psychological analyses 
depends on any such assumption. 

On the other question, which is frequently con- 
fused with the one as to the nature of matter and 
its relation to experiencible things;^ on the ques- 
tion, that is, of the relation between the experience 
and its content and the brain activities which ac- 
company this experience, and which may them- 
selves be made the content of experience, we must 
take the common-sense view that the relation is one 

^ By " matter '^ is meant either the atoms and ether, or what- 
ever physical science replaces these with. "Energy'' must 
also be included, or else assumed in addition. 

2 This confusion furnishes practically the whole substance 
of the time-honored dispute between the " interactionists " 
and the "parallelists." 



SENSATION IN GENERAL 27 

of cause and effect, although we know very little 
about the real nature of causation, here or elsewhere, 
and are moreover unable to find out just how the 
causal sequences occur in these cases. If any one 
is prejudiced the other way, and is determined to 
believe that there is no causal relation between brain 
and experience, he will probably find few instances 
herein in which our supposition makes less accept- 
able for him our exposition of facts and principles. 

3. The Lag of Sensation 

The sensation may or may not begin simulta- 
neously with the process in the cerebral cortex; 
there is no direct evidence on this point. Between 
the initial action of the stimulus on the end-organ, 
and the beginning of the sensation, there is an in- 
terval which we suppose to be due primarily to the 
time required to set in action the end-organ, the 
nervous path of conduction, and the cerebral ap- 
paratus successively. When the stimulus ceases to 
act on the end-organ, the sensation does not cease 
at once, but continues for a brief time; this per- 
sistence we suppose to be due to the fact that the 
neural apparatus continues in action after the dis- 
continuance of the stimulus. 

With a given strength of stimulus, the time re- 



28 A SYSTEM OF PSYCHOLOGY 

quired for the sensation to reach its maximal in- 
tensity after the beginning of the stimulus is less 
than the time required for the sensation to disappear 
after the cessation of the stimulus. The time re- 
quired to raise the sensation to any point of inten- 
sity lower than the maximal is less than the time 
the sensation will last after it reaches that same 
intensity in the dying-out process. 

The delay in the rise of the sensation to a maxi- 
mum, or to a definite point below the maximum, we 
designate as the initial lag of the sensation. The 
time required for the dying out of the sensation, 
from the point at which the stimulus ceases, is 
called the terminal lag. The terminal lag is greater 
than the initial lag, however the initial lag is de- 
fined in a particular case. 

We take practical advantage of the excess of the 
terminal lag over the initial lag in the mixing of 
colors by means of revolving discs. If the disc re- 
volves so fast that the retinal processes excited by 
a sector in any retinal area do not diminish appre- 
ciably in interisity before the sector again stimulates 
the same area, the effect is exactly the same as that 
of a constant stimulus, and, therefore, the sensation 
is steady. The initial lag operates in this case to 
effect a reduction of the intensity of the sensation 



SENSATION IN GENERAL 29 

below that which would obtain if the stimulus acted 
continuously. The passage of the sector across the 
point in the visual field occupies so brief a time (if 
the colors blend well) that before the physiological 
process has been raised to its full intensity the sec- 
tor has gone by. The intensity of the sensation 
produced by the intermittent stimulation is about 
the same as the intensity produced by the constant 
action of a stimulus bearing the same intensity ratio 
to the intermittent stimulus as the length of time 
the intermittent stimulus is present bears to the 
total time.^ This generalization is known as the 
Talbot-Plateau law. Possibly there are limitations 
to be made, but none are yet established. 

The other modes of sense are theoretically sub- 
ject to lag, and its occurrence may be demonstrated 
in the cases of audition and the dermal senses. 
Where the intermittence of a tone is rapid enough, 
the sensation becomes continuous and steady. And 

^ For example : A light stimulus which is so intermitted 
by means of rotating sectors, or otherwise, that the half- 
phase from disappearance to reappearance is exactly as long 
as the half-phase from reappearance to disappearance, will 
appear as bright as a stimulus of half the intensity contin- 
uously present. The frequency of intermittence necessary 
to produce a "smooth" mixture, ^. e., to avoid flicker, is in 
many cases over sixty per second; with dimmer lights a 
slower rate will succeed. This rate gives us no idea of the 
actual magnitude of either initial or terminal lag, but throws 
some light on the relation of the two. 



30 A SYSTEM OF PSYCHOLOGY 

a rapid succession of taps on the finger will fuse 
into a steady sensation. 

Intermittence of a stimulus modifies in an essen- 
tial way the resulting sensation or sensations. This 
modification is in some circumstances noticeable in 
light as a variation in quality, but is still more 
marked in the case of tones, because a large part of 
the range of the rates of sound vibration is within 
the range of intermittences which can be employed. 
The practical effect of intermitting a tone stimulus 
is to add to the sensation another tone having a 
pitch corresponding to the rate of intermittence, 
provided the said rate is faster than circa thirty per 
second. Below thirty, the result is merely the pro- 
duction of beats. It is sometimes said that the 
beats "fuse into a tone" when they become suf- 
ficiently rapid; there is no reasonable objection to 
that form of statement for the present. The new, 
or secondary, tone arises when two sources of sound 
differ by more than thirty vibrations per second, as 
well as when a single tone is mechanically inter- 
mittent; the tone in the one case mentioned is ac- 
cordingly called a difference tonCy and in the other 
an intermittence tone. There are difference tones 
of the first and second orders, corresponding to the 
two orders of beats. 



SENSATION IN GENERAL 31 

The production of a tone by a sound-wave is 
itself sometimes spoken of as the fusion of the 
processes aroused by intermittent stimulation, the 
sound-wave being considered as an intermittent 
affair. This is an error, for the sound-wave, when 
rapid enough to produce a tone sensation, is strictly 
a continuous stimulus. 

4. Secondary Sensations 

In many cases the sensation aroused by a given 
stimulus is followed by a secondary sensational con- 
tent, after the cessation of the stimulus in question, 
and without further essential stimulation. The sec- 
ondary sensation follows its primary sensation after 
an interval varying from a fraction of a second to 
several seconds. It may be of the same quality as 
the primary, or it may be of some other quality of 
the same mode. 

The secondary sensation is commonly called an 
"after-image," and is said to be "negative" when 
complementary in color, or opposite in temperature, 
to the primary sensation, and "positive" when of 
the quality of the primary. It is unfortunate that 
we have not a better terminology for these phe- 
nomena, for it is important that the secondary 
sensations be distinguished from the negative after- 



32 A SYSTEM OF PSYCHOLOGY 

images described in the chapter on sensation qual- 
ity/ The true negative after-image is produced by 
a stimulation which may be called secondary, since 
it follows the stimulus which conditions the pre- 
ceding sensation, and its operation depends on the 
results of that stimulus; but as a sensation, it is 
just as primary as the preceding sensation. 

Secondary visual sensations develop best after 
a brief stimulation by a strong light. Gaze for a 
moment at a gas flame, or electric light filament, 
and then turn out the light, having the room other- 
wise completely darkened. In a few moments an 
^' image of the light^' will appear, perhaps in its nor- 
mal color, perhaps in some other; it may seem mi- 
nute in size, and located in the eye itself; by a little 
practice you can succeed in projecting it to a dis- 
tance, when it will seem correspondingly large. A 
very slight movement of the eye will cause the sec- 
ondary sensation to disappear temporarily. 

5. The Characters of Sensation 

If we consider a single sensation, e. g., a certain 
red, and compare it with others, e, g., sweet or blue, 
we find that, although the sensation cannot be 
analyzed or resolved into simpler objects, and, there- 

^ Chap. IV, § 8. 



SENSATION IN GENERAL 33 

fore, is properly called elementary, yet it is not so 
simple that it has not several different aspects, or 
points of difference from other sensations. These 
aspects, or points of difference, are usually called 
characters, and a proper understanding of these 
characters is the indispensable foundation of the 
study of sensation. 

In the first place, a certain red differs from sweet 
and blue in a way in which it does not differ from 
other reds. This difference we call one of quality. 
It is a difference in kind of sensation. Next, there 
is a difference between certain reds of the same 
quality, as well as between reds and any other sen- 
sations, which we call intensity. We may increase 
the brightness of red without bringing any other 
color or sensation, so far as is observable. (In 
most cases, however, changing the intensity of a 
color involves the changing of the quality also, to 
some extent.) A spoonful of sugar in a glass of 
water will give a taste which is weaker (less intense) 
than two spoonfuls; and though we commonly say 
it is less sweet, we do not mean that the quality is 
different, but that the intensity is less.^ The weak 

^ The same language in regard to other sensations may 
mean a difference of quality, rather than of intensity. Thus, 
to say a light is less red than another usually means that it 
contains more of some other color. 



34 A SYSTEM OF PSYCHOLOGY 

sweet is no more like bitter or blue in quality than 
is the more intense sweet. 

A third character of sensation is volume or ex- 
tensity. A large patch of light differs from a small 
one even if of the same color and intensity. So a 
large touch on the skin differs from a small one. 
Similar differences may be found in muscular and 
auditory sensations, but that they may be found in 
all kinds cannot be said dei&nitely. Smell sensa- 
tions do not seem to have this character at all, and 
its presence is an open question with regard to 
taste. Extensity is sometimes confused with ex- 
tension, or perceived space; but in the latter the 
former is only one factor, as will be shown in the 
proper place. Extension is a function of a com- 
plex content, but extensity is just as original an as- 
pect of those sensations which possess it at all as are 
quality and intensity. 

The fourth aspect is duration, or protensity. 
Just as most sensations have extensity or inchoate 
bigness, which forms the beginning of our knowl- 
edge of space, so all have a magnitude of another 
sort which forms the basis of our perception of 
time. No sensation can be conceived which has 
not this temporal or enduring character. It may 
be roughly indicated by saying that a sensation 



SENSATION IN GENERAL 35 

which lasts no time at all does not exist. This, 
however, gives a slightly false implication, since 
the protensity of a perception does not imply the 
perception of time as such.^ 

Some sensations possess the important character 
of local significance. Thi ^ is an aspect which can- 
not be directly demonstrated, but which can, never- 
theless, be conclusively proved to exist. It is the 
character of a sensation by which, independently 
of its other aspects, we are able to determine the 
part of the body in which the neural process 
originates, or the direction in space from which 
the stimulus comes. The sensation from each 
part of the skin and retina has its peculiar local 
sign. 

Any sensation may be pleasant or unpleasant. 
By considering the neutral condition, in which 
there is neither positive pleasantness nor unpleas- 
antness, as simply the transitional point between 
the two, we may consider the triad as an aspect 
of sensation which is usually called feeling-tone. 
This so-called character is not strictly on a par with 
the ones previously enumerated, because, in the 



* Protensity is not quite the same as duration, in the com- 
mon acceptation of the term. This will be made clear in 
the section on time-perception. 



36 A SYSTEM OF PSYCHOLOGY 

first place, it can be considered as an accompani- 
ment of sensation, which the others cannot, and in 
the second place it is equally attached to other 
features of the content of experience besides sen- 
sations, in which cases it seems still more clearly 
to be an accompanying factor rather than an as- 
pect. 

The characters just named seem to exhaust the 
list. We find no other aspects under which sensa- 
tion must be viewed in and for itself, although of 
course we find it functioning in definite ways in the 
total content, and entering into different relations to 
consciousness. The catalogue stands then: quality, 
intensity, protensity, extensity, local significance, 
with possibly feeling-tone. 

In an advanced study of the psychology of sen- 
sation it is advisable to take up each group of 
sensations by itself, and to give it exhaustive treat- 
ment from all sides. In an elementary study, 
where the general principles are more important 
than the minute details, and in particular where 
sensation is studied in its connection with other 
content and with experience rather than for its 
own interest, the systematic treatment under the 
different aspects or characters is more useful. We 
shall, therefore, treat sensation first under its qual- 



SENSATION IN GENERAL 37 

itative aspect, and then under the other aspects in 
order. Such a programme cannot be adhered to 
absolutely, and there will necessarily be some over- 
lapping. 



CHAPTER IV 

SENSATION QUALITY 
I. General Classification 

The various qualities of sensation are commonly 
divided into groups, each of which is said to "be- 
long to" a definite sense. Red, green, and blue, 
for example, belong to the sense of vision and are 
called visual sensations. Bitter and sweet belong 
to the sense of taste, or gustation, and are called 
gustatory sensations. 

It is sometimes said that there are five senses, 
but as a matter of fact we discriminate several 
more than that number. There is much confusion 
in regard to the names applied to several of the 
senses and to the sensations which appertain 
to them, and still more confusion in the names 
applied to the sensibility or insensibility to certain 
sorts of sensation. The terms given in the follow- 
ing table represent the most justifiable usage, al- 
though not in all cases the most common: 

38 



SENSATION QUALITY 



39 



THE TERMINOLOGY OF SENSATION 



I 


II 


Ill IV 


V 


SENSE 


ADJECTIVES 


ANESTHESIA 


Taste. 


Gusta- 
tion. 


Gusta- 
tory. 


Geusic. 


Ageusia. 


SmeU. 


Olfaction. 


Olfactory. 


Osmic. 


Anosmia. 


Sight. 


Vision. 


Visual. 


Opsic. 


Anopsia. 


Hearing. 


Audition. 


Auditory. 


Acusic. 


Anacusia. 


Touch. 


Taction. 


Tactual. 


Haphic. 


Anaphia. 


Warmth-sense. 







Thalpotic. 


Athalposia. 


Cold-sense. 







Rhigotic. 


Arrhigosia. 


Tickle-sense. 


Titilli- 


Titilli- 


Gargal- 


Gargal- 




ation. 


atory. 


sesthetic. 


anaesthesia. 


Muscle-sense. 




:;::::! 


Kin aesthetic. 


Akinaesthesia. 


Joint-sense. 








Body-sense. 






Coensesthetic. 




Pain-sense. 






Algetic. 


Analgesia. 


Hair-sense. 







Tricho- 
aesthetic. 


Tricho- 
anaesthesia. 


Vibration-sense. 






Palmaesthetic. 


Palman- 
aesthesia. 



The first column contains the names for the 
senses, derived from various languages. In the 
second column are the corresponding words of 
Latin derivation. The third column gives the 
adjectives applying to the sensations. In a case 
where there is no specific adjective, the usual Eng- 
lish sense name is used adjectively; e, g., pain 
sensation, cold sensation. The adjectives from the 
Greek, given in the fourth column, indicate the 
sensibility, and should not be used to indicate 
either the sense or the sensation. 

The prefixes jpar- (para-), pseud-, (pseudo-), hyp- 
{hypO"), and hyper- are also used with the Greek 



40 A SYSTEM OF PSYCHOLOGY 

words (with the ia termination) to indicate specific 
aberrations of sensibility; as, for example, parop- 
sia, pseudosmia, hypokincesthesia. The prefix orth- 
(ortho-) is used to indicate the normal condition of 
the sensibility, as for example orthacusia. The 
suffix -meter is added to indicate the instrument for 
measuring the sensibiUty; for example, acumetery 
haptometer , algesimeter. Certain sense realms have 
also special prefixes to indicate peculiarities of sen- 
sibility found in these realms. Chromopsia, for 
example, indicates sensitivity to color; achromopsia 
indicates color-blindness; and for various aberra- 
tions of color sensitivity we have the terms para- 
chromopsia n dichromopsia, etc/ 

Each sense has its own end-organ or organs; 
that is, some mechanism for receiving physical stim- 
ulation and transmitting excitation to the brain; 
this is true both anatomically and histologically. 
But the sense cannot be defined by reference simply 
to the organ in either meaning. Some organs 
(grossly speaking) are vehicles for more than one 

^ The system of terminology for sense-psychology given 
above is the logical one, and is in common use, except for the 
terms for temperatm-e sensations. This system, however, 
is not exclusively used, there being the most deplorable con- 
fusion in regard to terms for almost all of the senses. Cer- 
tain terms are used by different authors in exactly opposite 
senses, and for some cases we have a variety of terms in use. 



SENSATION QUALITY 41 

sense. The eye gives visual, muscular, and temper- 
ature sensations; the ear auditory and organic as 
well as tactual; the tongue gustatory, tactual, and 
cold and warm sensations; the nose also gives tactual 
and cold and warmth as well as olfactory sensations; 
the skin gives several sorts of sensations. 

We might use the term organ in a narrower 
sense and say that the retina is the organ of vision, 
the cochlea the organ of hearing, etc., but this 
would be inaccurate; because the whole ball of the 
eye and its muscles are functionally concerned in 
vision, and form the organ; and so likewise the 
bones, membranes, and muscles, of the ear-drum 
are entitled to be specified as parts of the organ of 
hearing, since they participate normally in the pro- 
duction of the nervous process which conditions the 
experience of sound. 

If we wish to associate the visual sensation with 
its specific nervous terminals, excluding the acces- 
sory parts of the organ, we should have to take, not 
the retina as a whole, but the minute rods and 
cones therein, into consideration. In the same wav 
we should consider only the hair-cells in the basi- 
lar membrane of the inner ear in connection with 
auditory sensations. We might, therefore, with accu- 
racy specify visual sensations as those presented 



42 A SYSTEM OF PSYCHOLOGY 

through the activity of the nerve endings in the 
retina of the eye, and so on; and to this method of 
speech there can be no reasonable objection; but 
it gives no information about the sensations them- 
selves beyond the connection explicitly designated. 
It neither defines nor specifies the sensations, but 
presupposes their identification. 

The term '' sense '' is used very loosely. Some- 
times it indicates the group of sensations, sometimes 
the abstract possibility of experiencing these, and 
sometimes the entire physiological mechanism for 
the experience, including the histological organ. 
Accordingly, psychologists are accustomed to use 
the term "mode of sensation ^^ to convey with pre- 
cision the first of these meanings. The visual sen- 
sations taken as a group are said to constitute the 
visual mode of sensation; the olfactory sensations 
the olfactory mode, and so on.^ Modality is one 
step above quality in the logical classification of 
sensations. 

* Helmholtz defined a mode as a group of sensations related 
so closely that it is possible to pass from one to the other by 
a gradation so minute as to be practically continuous. (Hand- 
buch der physiologischen Optik, 1894, § 584.) This will be 
illustrated in section 6 of this chapter, in the case of visual 
sensations. The definition is not useful, since it gives no 
criterion for distinguishing a transition between two sensa- 
tions of the same mode from a transition between two sen- 
sations of different modes; hence the modality has always 



SENSATION QUALITY 43 

2. Sensation and Brain Process 
Each sensation quality depends on a specific 
kind of nervous process in the cortex of the brain, 
and each mode of sense seems to be dependent upon 
the functioning of a definite part of the cortex, which 
is called the " cortical centre," for that mode. Each 
mode, and perhaps in some modes each quality, is 
represented by certain peripheral nervous structures 
called "end-organs," and these are connected by 
sensory nerves with the corresponding centres.^ 

The cells of the sensory cortex are specialized to 
respond to the excitations poured in upon them by 
the end-organs with which they are connected. 
Whether they would (in the case of an adult) re- 
spond to a different kind of stimulation, is a matter 
for doubt. In the plastic condition of the develop- 
ing cortex (of the infant) it seems to be a fact that 

to be distinguished on other grounds. A continuously graded 
transition from heat to bitter, for instance, is perfectly possi- 
ble, and there would be no objection to considering it a 
transition within a mode, if we had not decided, on grounds 
having no reference to the question of gradations, that bitter 
belongs to one mode, and heat to another. The final deci- 
sion on a question of modality of elementary sensations 
must rest on the likeness and unlikeness of the sensations 
involved. 

1 See Howell, figs. 96-100, and pp. 198-228. Piersol, figs. 
102 and 1043; also figs. 1041, 1044, 909, 910, 987, 988. 
Schafer, figs. 330, 338, 340 and 351. 



44 A SYSTEM OF PSYCHOLOGY 

if certain cells which would normally respond to a 
definite sort of stimulation, e, g,, visual, be de- 
stroyed, other cells, either in the cortex or in the 
lower centres, may become so adapted as to respond 
to that sort of stimulus. In any case, it is the kind 
of stimulus furnished to the brain cell by the end- 
organ which determines its response. Direct irri- 
tation of the cells of the cortex by electrical currents, 
or by pinching or burning, produces no sensation. 
The character of the process in the end-organ is the 
thing of prime importance in determining the sen- 
sory function of the brain cell. 

3. Sensation of Taste 
Gustatory sensations are dependent on the stim- 
ulation of certain nerve endings, almost all of which 
are on the tongue. These nerve endings are in the 
"taste-buds," which are the peripheral organs of 
taste. They are found on the tongue in the walls 
of the circumvallate papillae and in the fungiform 
papillae, and also occur in the epithelium of the 
mucus membrane where there are no papillae.^ In 
the cases of infants and some adults a few taste- 
buds are found on the soft palate, gums, cheek- 
linings and even on the tonsils and hard palate. 

^Piersol, figs. 1193, 1194, 1195, 1196, 1197; Quain, III, 
pt. Ill, figs. 167, 168, 170, 172. 



SENSATION QUALITY 45 

The cortical centres for taste, or gustatory cen- 
tres, are on the inner sides of the hemispheres, 
probably in the hippocampal lobes. The course of 
the nerve-fibres from tongue to cortex is extremely 
complicated. One bundle runs through the tym- 
panum (ear-drum), and is hence called for that 
portion of its course the "chorda tympani.'' ^ 

Substances which are gustable (sapid substances) 
must be dissolved in water (or in some aqueous 
liquid; saliva is, of course, the common solvent), 
and so either enter the outer part of the taste-bud, 
or perhaps come in contact with the hair-like fibres 
of the gustatory cells projecting into the orifice 
leading to the bud. Substances insoluble in water 
are tasteless; but soluble substances are not always 
gustable. 

Although the number of "flavors" detectable in 
substances introduced into the mouth is indefinitely 
large, there are probably but four distinct element- 
ary taste quaHties. These are: sweet, salty, bitter, 
and sour ("acid"). These are the only sensations 
(except possibly "metallic" and another to be 
noted later) referable to the taste-buds, and are the 
only ones to be called tastes. The so-called "al- 
kali" taste is probably a combination of weak salty 
iPiersol, figs. 1075 and 1079; Howell, fig. 119. 



46 A SYSTEM OF PSYCHOLOGY 

with weaker bitter. " Hot " tastes, as of pepper, are 
due to the excitation of non-gustatory end-organs 
on the tongue and in other parts of the mouth, and 
are genuine warmth sensations, like those obtain- 
able from the skin of the hand or arm. The tongue 
is also sensitive to cold, and to touch; peppermint 
excites indirectly sensations of the former, and "as- 
tringent" substances, as alum and strong tea, ex- 
cite those of the latter. But the characteristic thing 
about what we call flavor in foods and drink is given 
through the sense of smell, as may be demonstrated 
in many ways. Every one has noticed the com- 
parative tastelessness of food during the course of 
a severe cold; this is the result of the interference 
of the catarrhal inflammation with the function of 
the organs of smell. Conclusive results may be ob- 
tained readily by stopping up the outer opening 
of the nostrils (anterior nares) and the inner open- 
ing (posterior nares) .^ The patient then breathes 
through the mouth and no aroma can possibly as- 
cend to the nostrils. The patient in the condition 
described is temporarily anosmic. If his eyes are 

* The posterior nares, of course, should not be meddled with 
except by a physician. But one can obtain fairly good re- 
sults by stopping the anterior nares alone (with pieces of 
cotton) provided the patient breathes gently. Vigorous 
breathing increases the diffusion of odorous substances into 
the nose through the posterior nares. 



SENSATION QUALITY 47 

shut, he can distinguish substances put into his 
mouth only in so far as they differ in regard to the 
five qualities we have mentioned, or in regard to 
their "feel'' (touch), or temperature. A few in- 
stances will illustrate. Tea, weak coffee, and a 
solution of quinine cannot be told apart if the 
strength of each is properly chosen. If the tea is 
very strong, the quinine solution may require a drop 
of alum water to be added to it to make it taste like 
the tea. Plain sugar and water cannot be distin- 
guished from molasses or almost any fruit syrup, 
properly diluted. Suitable mixtures of grain alco- 
hol and water, with sugar, and a few drops of alum 
water and vinegar (or acid-solution), as necessary, 
will counterfeit vinous or distilled liquors. These 
experiments may be extended indefinitely, and not 
only demonstrate the fewness of taste qualities, but 
will also show how very sensitive the tongue is to 
touch and to temperature, and how much our dis- 
crimination depends on these. It is well not to let 
the patient taste the solutions before his nostrils are 
stopped, or slight differences in viscosity, or strength 
of any element, may cause him to remember and 
distinguish them later, with no intention of trickery 
on his part. 

The functions oi- individual taste-buds have not 



48 A SYSTEM OF PSYCHOLOGY 

been satisfactorily examined, but experiments which 
have been made on single papillae (fungiform) show 
that some of them are sensitive to two qualities only, 
some to three, and some to only one, although there 
is some doubt whether there are papillae sensitive 
to bitter only. Seldom are papillae sensitive to 
all four qualities. Whether a single taste-bud 
can produce the nervous excitation of more than 
one taste quality is for the present an open ques- 
tion. 

The circumvallate papillae, and others near the 
base of the tongue, are especially sensitive to bitter. 
Papillae sensitive to sweet are grouped more numer- 
ously toward the tip of the tongue, and those sensi- 
tive to salt and sour on or near the edges. Sensi- 
tive papillae are few in the central area of the tongue, 
which some experimentors have reported as com- 
pletely ageusic; but, in general, all parts of the 
upper surface of the tongue possess some of the 
papillae sensitive to each of the gustatory qualities, 
although the details of distribution differ with the 
individuals, and some persons are, through disease, 
rendered totally ageusic. 

There is one content of experience which is com- 
monly called a "taste" which merits special atten- 
tion, since it is not included in any of the conditions 



SENSATION QUALITY 49 

we have here described. This sensation, or com- 
plex, which every one, no matter how temperate, 
has doubtless experienced, is commonly known by 
the picturesque name of the '* dark-brown taste/' 
It certainly is not salt, sweet, or sour, and the bitter, 
metallic or astringent components, if present, are 
not the main thing. Although due to visceral con- 
ditions, it is probably produced through stimulation 
of the nerves in the mouth, and so may have a cer- 
tain claim to be classed as a taste sensation. But 
there are other reasons why it may be classed with 
the organic sensations (ccensesthesia), and we shall 
discuss it further under that head. 

4. Sensations of Smell 

If the student looks on the nose as the organ of 
smell, with no further idea of the exact part of the 
nose which is sensitive, he will be somewhat sur- 
prised upon examining the nasal structure. The 
interior of the nose is a complicated cavern, or 
rather two caverns, communicating not only with 
the outer air and with the pharynx, but with cavi- 
ties in the bones of the face. The peripheral ner- 
vous apparatus of smell occupies only a very small 
area in the membrane covering a part of the supe- 
rior turbinal bone and of the adjacent portion of the 



50 A SYSTEM OF PSYCHOLOGY 

nasal septum. This region is known as the olfac- 
tory region, and this portion of the membrane as 
the olfactory membrane. The cells which receive the 
terminations of the nerve fibres are much like the 
gustatory cells of the taste-buds.^ 

The fibres of the olfactory nerve penetrate di- 
rectly through the skull to the olfactory lobes of the 
brain, and pass thence to the hippocampal lobe, 
especially the distal portion thereof, called the gyrus 
uncinatus. This is, therefore, the cortical centre 
for smell — the olfactorv centre. 

In order that it may be smelled, a substance must 
be in a gaseous state, and must be brought into 
direct contact with the olfactory membrane. How- 
ever fine may be the particles of a substance, if they 
remain mere particles, not becoming vaporized, they 
are without odor. Formerly it was thought that 
substances dissolved in water could be smelled if 
brought in contact with the membrane, but now it 
is known that such is not the case. Substances 
that are odorous also fulfil a definite chemical con- 
dition; the molecules which constitute them must 



^ On nose and peripheral terminations see Piersol, figs. 
1174, 1175, 1176, 1178, 1179, 1180; Quain, III, pt. Ill, figs. 
154, 156, 157, 158, 159, 160; Schafer, figs. 446, 447. On the 
neural connections, Piersol, figs. 1042, 1043, 1047, 1048, 1049; 
Howell, fig. 95; Schafer, figs. 351, 349. 



SENSATION QUALITY 51 

possess or exceed a certain minimum weight. This 
minimum is for most persons the weight of prussic 
acid (hydrocyanic acid), which substance is odor- 
less for these individuals. Other persons, whose 
osmic sensitivity extends slightly lower, find that 
prussic acid has a distinct odor. 

Constant presence may render any substance 
odorless; that is, an odor continuously present, 
finally disappears. Water vapor and carbon di- 
oxide, although gaseous and of suflBcient molecular 
weight, are odorless because always in the air. 
This is probably an instance of what is best desig- 
nated as protective adaptation. A sensory organ 
acted upon by a stimulus which it is functionally 
fitted to receive becomes by the action of the stim- 
ulus less responsive to it. This is not fatigue, which 
of course may produce a similar result; it is an 
antagonistic reaction by which the organ becomes 
protected against the action of the stimulus, just as 
the soles of the feet become protected by thicken- 
ing of the skin when no shoes are worn. The quick- 
ness and completeness with which one becomes 
insensitive to an osmic stimulation is a matter of 
common observation. The air in the room be- 
comes fetid from one of a number of causes, and 
you do not notice it until you return after being 



52 A SYSTEM OF PSYCHOLOGY 

out of the room some moments. People are, in 
general, immune to the odor of their own per- 
spiration. 

The number of elementary olfactory qualities is 
at present unknown. We are obliged to treat them 
as if they were indefinitely numerous, and yet there 
may be really only a few, which by combination in 
endlessly different ways give rise to the riotous pro- 
fusion of odors which constitute our olfactory world. 
The suggestive similarities which run criss-cross 
through this world point to this theory, but so far 
we have not been able to make any scientific use 
of those similarities. Classification by qualitative 
affinity has been attempted; a great many natural- 
ists since Aristotle have tinkered with the problem ; 
the most laudable attempt being made by the bot- 
anist Linnaeus, to whose catalogue Zwaardemaker 
has added two more titles. The result of all these 
efforts has been of slight value theoretically or practi- 
cally. The classes of Linnaeus are nicely exempli- 
fied by certain odors, but when you attempt to 
classify a large number of odors according to the 
scheme, you find that many belong equally well 
under two or more headings, and others refuse to fit 
anywhere. The types selected evidently do not 
represent anything fundamental. 



SENSATION QUALITY 63 

LINNiEUS' OLFACTORY CATEGORIES. EXAMPLES 

1. Aromatic Turpentine; lavendar; camphor; spices; 

butyric ether. 

2. Fragrant Flowers; vanilla; benzoin. 

3. Ambrosiac Musk; ambergris. 

4. Alliaceous Garlic; assafoetida; CI.; Br; CS^. 

5. Hircine Cheese; sweat; rancid oil; lactic acid. 

6. Repulsive, or 

Virulent Opium; nightshade family. 

7. Nauseous Decaying animal matter. 

zwaardemaker's additions 

a. Ethereal Fruits; some essential oils and ethers. 

b. Empy rheumatic . .Toast; tobacco smoke; tar; coffee; gas- 

olene; creosote. 

Although the attempt at classification has been 
a failure, some hope has been aroused by the dis- 
covery, by Sir William Ramsay and others, that cer- 
tain substances with similar molecular structure 
have similar odors, and that in a group of substances 
of similar structure (as the alcohols) the pungency of 
the odor increases with the molecular weight. Al- 
though there are exceptions enough to make the 
connections merely interesting and suggestive, it 
seems certain that in sensations of smell we come 
closer, so to speak, to the unexperiencible matter 
than in sensations of any other mode. 

Individuals differ in their sensitiveness to odors 
even more than they do in regard to taste. Some 
persons are osmically as keen as the lower animals ; 



54 A SYSTEM OF PSYCHOLOGY 

others are very obtuse to odor, and some are com- 
pletely anosmic from birth. Catarrh, or other dis- 
ease, may largely or completely rob the victim of 
his sense of smell. Other details of osmic sensi- 
tiveness will be mentioned under intensity. . 

5. Visual Sensations 

The nerve endings which condition the produc- 
tion of visual sensations — the rods and cones — are 
in the retina, the lining of the eyeball. The other 
parts of the eye are important as means for the 
bringing of the rays of light to bear properly on 
those endings.^ 

The fibres of the optic nerve pass from the rods 
and cones through the midbrain beneath the hem- 
isphere to the occipital lobes, the rearmost portions 
of the hemispheres; and these, with the addition of 
certain contiguous areas, constitute the visual cen- 
tres.^ 

Opposite to the pupil of the eye there is a little 
depression in the retina, about two and one-half 
square millimetres in area, called the fovea. While 
not so sensitive to light as are the surrounding areas, 



1 Piersol, figs. 1202, 1203, 1214, 1218, 1220, 1221, 1222, 1223; 
Quain, figs. 45, 48, 52. 

2 Piersol, fig. 1050; Howell, figs. 91, 92. 



SENSATION QUALITY 55 

it is capable of finer discriminations; or, as we say, 
the visual acuity is greatest here; hence, the eye is 
commonly moved so that the image of whatever we 
are attending to, or the most important part of that 
image, falls on the fovea. Only after considerable 
practice can one attend to a definite part of the field 
of vision without automatically turning the eye to- 
ward it so that its image falls on the fovea. The 
fovea contains no rods, but only cones, and they 
are here covered by a thinner layer of nervous tis- 
sue than elsewhere, so that the light reaching them 
is less dispersed, i, e,, is brought to a sharper focus 
here than elsewhere on the retina. 

A short distance from the fovea is the spot at 
which the optic nerve enters the eyeball. This spot 
is insensitive to light because there are here neither 
rods nor cones, and is hence called the blind-spot. 
The blind-spot does not inconvenience us in ordi- 
nary vision because it is so situated in the retina that 
the portion of the image which falls on the blind- 
spot of one eye does not fall on the blind-spot of the 
other. 

We can discuss color only by reference to the 
solar spectrum, and the student should, if possible, 
examine the spectrum, either projected on a screen 
or viewed through a spectroscope. Failing the 



56 A SYSTEM OF PSYCHOLOGY 

actual spectrum, colored charts of it may be used. 
Several such charts are published but are not chro- 
matically true. 

The prism of the spectroscope spreads out the 
light- waves coming through a narrow slit into a di- 
verging beam at one side of which there are long 
waves and at the other short waves, the wave length 
in the intermediate portions varying accordingly. 
If now this beam of light falls on the retina through 
proper lenses, or after being intercepted by a screen, 
a band of colors — the "spectrum" — is formed, rang- 
ing from the red produced by the least frequent 
(longest) waves, through the orange, yellow, green, 
blue, to the viblet of the most frequent (shortest) 
rays; and as the wave length decreases continuously 
from one end of the spectrum to the other, so the 
red merges smoothly into the orange, the orange 
into the yellow, and so on, through the intermedi- 
ate hues of orange-red, red-orange, yellow-orange, 
orange-yellow, etc. Here we have an excellent 
example of a sensation-continuum; a series of sen- 
sations passing one into the other without discrete 
gradations; that is, without break. 

Although there are a great number of hues in the 
spectrum, there are only a few elementary color sen- 
sations, and the other hues are composed of these 



SENSATION QUALITY 57 

in diflFerent proportions. That such uniform grada- 
tions can be produced by mixture is clearly shown 
by mixing the light-rays from the ends of the spec- 
trum, in which case a continuous gradation of pur- 
ples is obtained, ranging from the spectral red to the 
spectral violet: a series which is not in the spec- 
trum, but which, with the spectral hues, makes the 
total of colors within our experience. 

Inspection shows that the orange is a composite 
color involving red and yellow; that the hues be- 
tween green and blue are really only blendings of 
green and blue; and so the sensation-continuum 
here is not different in kind from the series of blend- 
ings of bitter and sweet, sweet and sour, etc., al- 
though it is more readily displayed. We are jus- 
tified, therefore, in assuming that there are a few 
fundamental colors, just as there are a few tastes, 
and that the combination of these produces all the 
hues with which we are familiar.^ In seeking for 
these fundamental colors we reject the orange, the 



^It is sometimes said that a "mixed'' color, e. g,, orange, 
does not contain other colors (red and yellow, in case of 
orange), but merely is like them, being really as simple as 
they are. On this postulate a psychology of color has been 
built up, but has so far not justified itself. We think it much 
more rational to proceed on the simpler postulate, on which 
all advance in the knowledge of color theory is actually 
founded. 



58 A SYSTEM OF PSYCHOLOGY 

blue-greens and green-blues, the yellow-greens and 
green-yellows, and the extreme violet as being ap- 
parent mixtures. We have left as presumably fun- 
damental colors: red, yellow, green, and blue or 
violet-blue; and these, or certain specific portions 
of them in the spectrum, seem to be truly element- 
ary. But in the consideration of them two peculiar 
circumstances are at once discovered, which merit 
careful attention. 

In the first place, there is no direct qualitative 
transition between the red and the green, and none 
between blue and yellow. That is to say: while 
you may arrange between red and blue a continuum 
involving only these two colors (the red-blues or 
purples); and between blue and green a similar 
continuum of green-blues and blue-greens; and 
between green and yellow a continuum of green- 
yellows and yellow-greens; and between yellow and 
red a continuum of yellow-orange, orange, etc., the 
yellow-blues and the red-greens are lacking. The 
transition in either case involves one of the other 
supposedly elementary colors, or else white (gray). 
We can, for example, pass from red through orange 
and yellow, or through purple and blue, or through 
pale red (pink), gray, and pale green; but never 
through red-greens. Yet, if red and green are ele- 



SENSATION QUALITY 59 

mentary colors we surely ought to be able to com- 
bine them as well as any other pair. This at once 
suggests that the four colors are not on the same 
plane. 

In the second place, the combination of green 
rays and red rays in diverse proportions (as regards 
intensities) gives the transition colors through yellow, 
while analogous combinations of yellow and blue 
rays produce the transition colors through white 

(gray). 

These relationships lead to the conclusion (first 
formulated as a scientific theory by Thomas Young), 
that yellow is not an elementary color, but is really 
red-green, and that gray is the composite of the 
three elementary colors, red, green, and blue (or 
indigo). This is the so-called " Three-Color Theo- 
ry," or "Young Theory'' — often called the 
" Young-Helmholtz Theory.'' According to it, the 
three colors are supposed to depend each on a 
specific process in the retina and in the brain (chro- 
moptic process) the nature of which is unassigned; 
and each of these three processes is supposed to be 
excited by light from all parts of the solar spectrum, 
but most strongly from one particular region (see 
fig. 5). The yellow portion of the spectrum is so 
colored because the rays from that portion excite 



60 A SYSTEM OF PSYCHOLOGY 

both the red and green processes rather strongly; 
while the rays from the blue-green portion excite 
both the blue and the green processes strongly. 

This theory, as it has been developed by Helm- 
holtz and others, succeeds in referring to one logical 
scheme all the facts of visual sensation yet discov- 
ered; but in its looser statement it has encountered 
one serious criticism. This criticism is that yellow 
cannot be introspectively analyzed into red and 
green, and gray into red, green, and blue. Exam- 
ine pure yellow as intently as you may, and you can- 
not find any red or green in it, and gray, if it is pure, 
is ipso facto neither reddish, greenish, nor bluish. 
This consideration has led many physiologists and 
psychologists to hold to the theory of Hering, or 
to variants of his theory. They hold that there 
are four colors — and four retinal processes, with an 
additional process for white. They even assert that 
black is an elementary sensation, and assign a sixth 
retinal process to it. These six processes are in pairs, 
the members of each pair opposing each other. 
We cannot go into the details of this theory, 
or the many objections to it. It is a noteworthy 
fact that the practical working out of the theory 
obliged its adherents to abandon the very psycho- 
logical grounds on which they started, by assuming 



SENSATION QUALITY 61 

as a fundamental color either blue-green or reddish- 
purple/ 

The three-color theory, as first proposed, implied 
the composite nature of the sensations of white and 
gray, and assumed that a "color-blind" (see below) 
person lacked one or two of the three processes. As 
a matter of fact, the first point is not essential to 
the theory; for all that is necessarily assumed is 
that when the "red'' process and the "green'' proc- 
ess are active together at certain relative intensities, 
the sense-content yellow arises. So, the theory need 
not insist on white as a complex, but may allow 
the alternative opinion. That is to say; the three- 
color theory is not necessarily a three-sensation 
theorv. 

In behalf of the three-sensation theory, however, 
it must be said that the fact that a content of ex- 
perience cannot be directly analyzed does not prove 
it to be simple. Of course we may assume such to 
be the case, and a certain sort of psychology does 
make that assumption to cover certain convenient 
cases. If the assumption were applied in a thor- 
ough-going way it would make psychological analy- 



^ For further details of the Hering theory see Rivers, 
(Schafer), pp. 1112-1121. On the Young theory, idem, 
1106-1112. 



62 A SYSTEM OF PSYCHOLOGY 

sis impertinent, to say the least, and experimental 
psychology is based on the denial of this assumption. 
As for color-blindness, whatever the earlier ad- 
herents of the theory may have held, the present 
adherents hold that in the common cases of color 
abnormality the three processes are present, but 
have an unusual range of excitability, as will be 
explained later, although it may be that in some 
cases there may be one or more of the processes 
lacking.^ 

6. The Schematic Representation of Visual Qualities 

The whole range of color hues may be repre- 
sented (as they might actually be presented) in the 
following way. Suppose three circular patches of 
light partially superposed as in fig. 1. Let one 
patch of light be of each of the three fundamental 
colors, and let the intensity of each patch be maxi- 
mal at its centre, falling off gradually to zero at the 
edge. We have then in the triangle of which N is 
the centre (leaving now out of account all the un- 

^The three-color theory in the five-sensation form has been 
given an evolutionary setting by Mrs. Franklin, who assumes 
that gray is the primitive color phylogenetically; that in the 
second stage of development yellow and blue arise by a dif- 
ferentiation of the "gray-process'^ into two new processes, 
and that in the third stage red and green arise by a differ- 
entiation of the "yellow-process." 



SENSATION QUALITY 63 

superposed and two-ply parts) all the colors, rang- 
ing from the full hues along the boundaries, through 
paler tints, to neutral gray or white near the centre. 
This representation introduces us at once to a 
characteristic of color sensations which is desig- 
nated saturation, A color is said to be saturated in 





Fig. 1. Fig. 2. 

proportion as it does not contain white or gray; the 
more gray the color contains (that is, the paler it is), 
the less the saturation is said to be. 

If we suppose the three fundamental colors to be 
taken in their maximal saturation, we can represent 
all visible hues in every possible saturation by such 
a triangle as that in fig. 1, in which the pure funda- 
mentals stand at the vertices. For convenience we 
draw the sides of the triangle straight, as in fig. 2; 
but it must be understood that the exact form of the 
triangle is insignificant — the fact that we have 
drawn it isosceles does not imply that the difference 



64 



A SYSTEM OF PSYCHOLOGY 



between R and G is equal to that between R and B, 
etc., for these differences are incommensurable. 
We might, indeed, use a circle in place of a triangle, 
locating the fundamental colors thereon at appro- 
priate points; and this "color circle" is frequently 
employed in preference to the "color triangle/' 





Fig. 3. 



Fig. 4. 



Now, we may wish to represent different inten- 
sities of color; this we may do in the dimension at 
right angles to the plane of the " color triangle.'' If 
we wish to represent another complete series of hues 
at an intensity uniformly higher than those just sup- 
posed to be represented by the triangle, we do it by 
a second triangle above and parallel to the first, 
as in fig. 3. In ttiis connection we find the peculiar 
fact that if we start with that intensity of a pure 
spectral light which gives the maximal saturation, 
and steadily increase the intensity, the saturation of 
the sensation soon begins to decrease, and at a cer- 



SENSATION QUALITY 65 

tain high intensity of the stimulus the color becomes 
white. Schematically, this would mean that the 
triangles must be drawn smaller and smaller, as we 
go up, until they become points. In decreasing the 
intensity the same phenomenon is met; all colors 
becoming gray (red is possibly an exception) before 
being extinguished; the saturation-decrease being 
more sudden at this end. 

The quahtative changes perceived as a light stimu- 
lus of practically homogeneous wave length is pro- 
gressively increased from zero to a maximum, are 
shown schematically in fig. 4. The line w pz is the 
series of grays, or neutral sensations, and is, there- 
fore, conceived as perpendicular to the color tri- 
angle (or color circle) at the centre. 

The interval z k, in which the stimulus arouses 
only the sensation of gray; the interval, therefore, 
between the light-threshold and the color-threshold, 
is called the photochromatic interval. Logically, 
there is an upper photochromatic interval also, but 
it is not susceptible of measurement because of the 
incident damage to the eye. 

Since the rate and the magnitude of change are 
represented here purely schematically, we may rep- 
resent any hue by a curve of the same form. Rang- 
ing them all around the common gray-axis, we 



66 A SYSTEM OF PSYCHOLOGY 

derive (i, e., by rotating fig. 4 on the axis iv p z) an 
onion-like figure, which, taken as a solid, contains 
schematically all possible visual sensations.^ Linear 
distance parallel with the axis represents intensity- 
change; linear distance perpendicular to the axis 
represents saturation change; and angular distance 
about the axis represents change of hue. 

Since white (gray) is equivalent to a certain pro- 
portion of red, green, and blue, it is evident from 
the color triangle that, for any color, we can find 
another color which when mixed with it will pro- 
duce gray, provided the intensities of the two are 
properly chosen; for all points on the triangle (ex- 
cept the vertices) represent combinations of two of 
the fundamental colors: and to any combination of 
two it is possible to add one of them and the third in 
such proportions that the proportions of the three 
shall be whatever is desired. And practically the 
conditions are quite easy of fulfilment. Colors 
which combine thus in pairs to produce gray are 
called complementary. Examples of complement- 
ary colors are: red and a certain blue-green; or- 

^ This is the tri-dimensional figure on the basis of the color 
circle. It might be constructed on the basis of the triangle, 
only the description of the generation is a little more difficult. 
Commonly, the line z mw, of fig. 4, is made a semicircle or else 
two straight lines, from m to w and m to z. The solid figures 
become then a sphere or a double pyramid or a double cone. 



SENSATION QUALITY 67 

ange and greenish-blue: yellow and indigo-blue; 
green and reddish-purple. 

We have used the terms white and gray inter- 
changeably. White is a relative term denoting the 
brightest gray. Any piece of paper which looks 
"white" may, if placed on a still whiter one be 
made to be a dull gray; and the new "white" may 
be literally put in the shade by a still brighter. 
"Black," too, is purely relative. The blackest 
paper obtainable looks dark gray against a black 
velvet. Black and white are contents of conscious- 
ness, but not sensations simply; they are complex 
sensations of gray perceived in certain relations. 
The difference between the various neutral grays 
is one of brightness only, that is, they form an in- 
tensive series of identical quality (whether we con- 
sider it a simple quality, or a mixture of three). 

7. Achromopsia and Parachromopsia 

Individuals differ in the sensitiveness of their 
color processes to the action of light of various wave 
lengths, and in the cases of some persons the varia- 
tion from the normal is so considerable that these 
persons are called color-blind. In extreme cases the 
patient can see no color at all, everything appearing 
to him gray; so that the landscape which shows 



68 A SYSTEM OF PSYCHOLOGY 

to US a wealth of hues presents itself to him as a 
black and white sketch. Yet the color-blind man 
may not realize that his vision is different from yours, 
and if you ask him the color of the grass he will say 
''green/' for he has always heard it called so, and 
has no way of knowing that "green" does not mean 
to you the same particular shade of gray it does for 
him. Such a person is said to be totally color-blind, 
or achromopsic. 

More numerous than the ''achromopes'' are per- 
sons who see colors, but not as we see them; they 
are called partially color-blind, or par achromopsic; 
parachromopes. The commonest case is that in 
which only blue and yellow are seen (in addition to 
gray), the normal red and green of the spectrum 
appearing yellow and a certain part of the blue-green 
appearing gray, as does also a certain purple (not 
in the spectrum, of course, but mixed from blue and 
red), which is to the normal eye complimentary to 
this blue-green. This is a typical sort of dichro- 
mopsia (two-color vision). Other persons see some 
green in addition to the gray, yellow, and blue; 
others probably see gray, red, and one other color; 
and still others see only gray and one color, which 
is probably green in some cases. 

How large the list of color abnormalities in vision 



SENSATION QUALITY 69 

— parachromopsias — may be, we cannot even guess, 
as yet, but enough is known to assure us that it is 
not small. The detection of these abnormalities is 
of great importance for railroad and nautical pur- 
poses, but is difficult, and possible only by skilfully 
arranged tests. Exact work can be done with spec- 
tral light and elaborate apparatus, but rough tests 
can be made with colored worsteds or silks. A few 
cases have been found in which the patient had one 
eye achromopsic, or parachromopsic, and the other 
normal, or nearly so, so that he could tell just what 
colors were seen with the defective eye; and these 
cases have given indispensible assistance in diag- 
nosing the color defects of others. 

We must distinguish between true parachromop- 
sia and mere lack of memory for hues, or inability 
to name them properly, or awkwardness in sorting 
them. While it is true that a genuine defect may 
escape detection sometimes, it is also true that a 
person may fail miserably in a color test, and yet be 
chromopsically normal, just as a nervous patient 
may, by confused reports on the oculist's tests, be 
convicted of serious astigmatism, and yet not be 
astigmatic at all. It is said that there are more 
color-defective men than women, but this may be 
doubted. Women are much more apt to escape 



70 



A SYSTEM OF PSYCHOLOGY 



detection, even by themselves, because of more prac- 
tice in handling colors. 

The totally color-blind person is apt to be able to 
see in a dim light better than a normal person, and 




to find unbearable a light which is for the normal 
person reasonably strong. This suggests at once 
the possibility that all three color-processes are 
present in his eye, and that they are alike excitable 
by rays of light of any wave length included in the 
spectrum. This hypothesis is also necessitated by 



SENSATION QUALITY 



71 



the fact that in cases of monocular achromopsia 
gray is seen aUke by both eyes. This condition is 
represented by the curves in fig. 8, where the achro- 




FiG. 8. 



mopsia is nearly complete; if complete the three 
curves would exactly coincide throughout. Fig. 5 
gives the probable relations of excitability of the 
three processes in the normal eye, showing how 
each color is excited by practically all rays of the 



72 A SYSTEM OF PSYCHOLOGY 

spectrum, but principally in a certain range. In 
these and the following curves the horizontal axis 
represents the spectrum, and the ordinate at any 
point represents the relative degree of excitation of 
the process by the light from that point in the spec- 
trum. The curves are not intended to represent 
any specific ratios, only the general positions being 
in point. Exact forms for the curves have been com- 
puted by several theorizers, but such computations 
are, after all, of little value, since they represent the 
carrying out of the results of certain postulates. 

Curves I, II, and III, in fig. 5, show the probable 
relative excitability of the red, green and blue proc- 
esses respectively, for the normal eye. Curve IV 
represents the relative brightness of the different 
parts of the spectrum as determined by the flicker 
method. Curves I, II, and III are so drawn that 
the sum of their ordinates at any point on the spec- 
trum (X-axis) is equal to the ordinate of curve 
IV at that point. 

Curves I, II, and III in figs. 6, 7, and 8 are ar- 
bitrarily modified from the curves in fig. 5, so that 
they may represent the color-vision abnormalities 
described. Curve IV in these figures is, accordingly, 
derived by summing the ordinates of curves I, II, 
and III. 



SENSATION QUALITY 73 

Fig. 6 shows the probable excitability of one type 
of yellow-blue parachromopsia (red-green blind- 
ness), in which the spectrum is of practically normal 
length. This was formerly supposed to be "green- 
blindness" and is often designated by the term 
"proteranopia." Fig. 7 represents the excitability 
in another type of yellow-blue parachromopsia, 
where the spectrum is shortened; formerly called 
"red-blindness"; "deuteranopia." There are all 
sorts of parachromopsias intermediate between these 
two, constituting, as we said before, the more numer- 
ous sorts of color-blindnesses. Other abnormalities 
than "yellow-blue" vision are known to exist, and 
may be represented by proper modification of the 
curves.^ 

The normal eye is not equally sensitiye to Hght 

^ The tri-chrome theory must not be understood as an 
explanation of the facts of "color-blindness," or of the other 
complex phenomena of color vision. It is merely a compre- 
hensive statement of all the facts; a descriptive theory, in 
short. It is not the only possible statement, but has the vir- 
tue of being the simplest. We can, for example (contrary, 
it is true, to general opinion), give just as thorough a state- 
ment with red, yellow, and blue as the fundamental colors, 
and work it out logically to cover all the known facts; but 
it would be more complicated. A slightly less complicated 
theory than this might be constructed with four fundamental 
processes and colors — it is all a matter of drawing the curves 
for the normal spectrum. Still other possibilities are open, 
but for the present it seems best to rest on the simplest state- 
ment. 



74 A SYSTEM OF PSYCHOLOGY 

and color In all parts. At the centre of the retina 
colors are discriminated with the greatest ease, but 
as you go out toward the edge of the visual field 
discrimination becomes more diflScult, and the col- 
ors lose in saturation until at the extreme limit of 
visibility they are practically all gray. It is some- 
times said that the margin of the retina is totally 
color-blind, and the zone intermediate between the 
margin and a certain central area, red-green blind. 
This is only partly true. The angular distance 
from the centre to which any color can be carried, 
and yet be visible in its proper hue, depends on 
practice, intensity, area, and duration. With intense 
spectral light, lasting but an instant, the colors can, 
after considerable practice, be discriminated nearly 
to the periphery. 

8. Color Adaption and Contrast 

Protective adaptation is especially noticeable in 
the visual realm, but takes several forms. In addi- 
tion to the control of the stimulus by the iris and 
of the sensitivity of the nerve-endings by the retinal 
pigment, there are adaptive changes which go on 
either in the retina or in the brain, by virtue of 
which any stimulus tends to produce a sensation 
which becomes more and more gray as the stimu- 



SENSATION QUALITY 75 

lation continues. The most familiar example of 
this phenomenon is found in yellow lamplight, 
which soon loses its yellowness if we are under its 
illumination exclusively. The change is also rapid 
in lights which are yellow-green, bluish-green, or 
purple; blue changes less rapidly, and red very 
slowly. The change is not essentially connected 
with loss of total intensity, and so is not to be con- 
fused with fatigue. 

In terms of the tri-chrome theory, color adapta- 
tion is a decrease in sensitiveness of processes 
strongly stimulated, with increase in sensitiveness of 
processes feebly stimulated. If, for instance, blue- 
green light is cast on the retina, the blue process and 
the green process are strongly excited, the red proc- 
ess hardly at all; the result is a sensation com- 
plex in which blue and green predominate. As 
the light continues to act, the blue and the green 
processes respond progressively less and less, 
and the red process more and more, so that the 
sensation complex becomes less and less satu- 
rated. 

The results of these adaptative changes are clearly 
shown when colorless (gray) light, e, g,, from a gray 
wall or paper in ordinary daylight, is allowed to fall 
on the part of the retina previously stimulated by 



76 A SYSTEM OF PSYCHOLOGY 

the colored light. Under these conditions the proc- 
ess or processes that have increased in sensitivity 
respond more intensely than the process or proc- 
esses that have decreased, and the result is a tinge 
of the color complementary to the original color. 
This color effect occupies the exact retinal area 
occupied by the exciting color, and its appearance 
is known as the negative after-image} 

The quahty of a light is determined, in the case 
just mentioned, by the intensive relations of the 
physio-psychological color components. In all cases 
the hue of the sensation roused by any given stim- 
ulus is a variable affair, depending on the condi- 
tion of the portion of the retina on which the stim- 
ulus falls, and on the condition of the adjacent 
retinal areas. The latter factor determines what is 
known as color contrast, or, to distinguish it surely 
from the after-image effect, simultaneous contrast. 
If you look at a small gray card placed on a large 
colored surface, you get the contrast effect very 
clearly: the card will appear tinged with the color 
complementary to that of the background. The 



^ Adaptation may take place, and be followed by the 
characteristic negative after-image, without any sensation of 
color during adaptation being noticed. This may be demon- 
strated by placing the subject in colorless light, to which 
minute amounts of a color are continuously added. 



SENSATION QUALITY 77 

eyes must not move during this observation, but 
must remain steadily fixed, or after-images will 
occur, and counterfeit the effect; slight movements 
will unavoidably occur, giving rise to narrow after- 
image effects along the edges of the card; so-called 
edge-contrast. The saturation of the contrast-color 
may be increased by covering the card and back- 
ground with a piece of tissue-paper or ground glass; 
by squinting through the nearly closed lids; or by. 
darkening the room (as by pulling down the win- 
dow-shades). No matter what the brightness and 
saturation of the colored background, or the bright- 
ness of the gray, one of these changes will heighten 
the contrast-color. 

No satisfactory explanation of the contrast effect 
has as yet been found, but the most plausible theory 
is that substances essential to the processes in the 
retinal area stimulated by the colored rays are 
drawn from the area stimulated by the gray, leav- 
ing that area, therefore, more sensitive to the other 
rays of the spectrum, because relatively better sup- 
plied with substances reacting to those rays. Of 
course the basis for this phenomenon, as well as for 
that of after-images, may not be in the retina, but 
may be in the brain; there is absolutely no means 
of deciding at present between the two possibilities, 



78 A SYSTEM OF PSYCHOLOGY 

but the fashion is to suppose that the retinal hy- 
pothesis is the true one. 

An interesting experiment which possibly demon- 
strates the transfer of photochemical substance 
across the retina, may be performed with an '' Archi- 
medean spiral," in black and white, on a pasteboard 
disk; this is supplied in the Miinsterberg set of il- 
lusions (by the Milton Bradley Co.). If the disk 
is rotated steadily — a clock-work or electric motor 
with controllable speed is best, but a hand-power 
color-mixer will do — at such a rate that when the 
eyes are fixed on the centre, rings run outward, 
like those from a stone dropped in the water; if 
these rings are observed several seconds (the eyes 
not moving), and if the eyes are then quickly closed 
and covered with a large piece of black cloth, 
"retinal streaming'^ will be observed, the bright 
streamers running from edge to centre of the dark 
field. If the disk is rotated in the opposite direc- 
tion, so that the rings run toward the centre, the 
streaming will be from the centre out. The closing 
and covering of the eyes must be very. quickly done; 
the cloth being held on the palms of the outspread 
hands ready for action while observing the rings. 
After some practice the streaming can be observed 
by simply closing the eyes, without covering. A 



SENSATION QUALITY 79 

more striking method is to have a single source of 
Hght, which illuminates the disk brightly, and to 
cut this light off at the proper moment, leaving the 
room in total darkness. Turning out an electric 
light will not do, as the light dies too slowly. 

The streaming may be observed on the disk itself 
while it is in rotation; it is in the direction of move- 
ment of the rings, and gives them a peculiar wavy 
appearance. On looking suddenly at some other 
object, the streaming in the reverse direction makes 
the object seem to expand or shrivel up in an odd 
way. 

If we assume a definite "color substance ^^ in the 
retina corresponding to each of the three hypotheti- 
cal color processes, . then it is a natural step to as- 
sume that these substances are attracted to the re- 
gion stimulated by the white rings, and so drawn 
outward (or inward) with the rings. This is ren- 
dered still more probable by the occurrence of what 
are known as "Fechner's colors"; as you look at 
the disk, it will sometimes take on a red or green 
cast; other colors occur seldom. This can be ex- 
plained by stronger attraction for one of the sub- 
stances, when the rate of rotation of the disk is such 
that following rings coincide with the greatest con- 
centrations of one of the substances. 



80 A SYSTEM OF PSYCHOLOGY 



9. Auditory Sensations 

The nerve endings of the acoustical apparatus 
are in the cochlea of the ear/ and the cortical cen- 
tre is in the superior temporal convolution.^ The 
acoustical stimulus is a vibratory movement of the 
air/ which is communicated through the external 
auditory meatus to the middle ear (tympanum), and 
thence through two windows (fenestra ovalis and 
fenestra rotunda) in the bony wall to the vestibule 
and cochlea. It was formerly supposed that the 
little bones (ossicles) transmitted the vibration from 
the tympanic membrane to the oval window into 
which the head of the stirrup bone is fitted, it being 
thought to act like a piston; but the discovery of 
individuals whose ossicles have been destroyed, and 
who hear nearly as well as normal persons has 
ruined this theory. It is probable that the air of 
the tympanum conducts the sound, and the bones 
act as a damper. Vibrations may be carried to the 

1 Piersol, figs. 1242, 1247, 1248, 1251, 1252, 1255, 1256, 
1257, 1259, 1260, 1264, 1268, 1271, 1272, 1273; Quain, III, 
pt. Ill, figs. 78, 87, 102, 108, 111, 113, 129, 131, 135, 136. 

2 Piersol, figs. 1042, 1043, 1071; HoweU, figs. 93, 94; 
Schafer, fig. 351. 

3 Hallock (Duff), pp. 301-307; Zahm, pp. 21-53; M'Ken- 
drick and Gray (Schafer), pp. 1149-1168; Howell, pp. 371- 
375. 



SENSATION QUALITY 81 

middle ear through the bones of the skull, and so 
reach the inner ear. You may test this by touch- 
ing the head to any object emitting feeble vibrations, 
as a tuning-fork, violin, or piano, faintly sounding. 

The exact manner in which the direct excitation 
of the auditory nerve endings (hair-cells on the 
basilar membrane) occurs has been the subject of 
much speculation. The Helmholtz "piano-string" 
theory was formerly held to be a satisfactory expla- 
nation, and, indeed, it is in accord with many of the 
psychological and pathological facts of audition; 
but, nevertheless, the anatomical details of the coch- 
lea are now believed to be against that hypothesis. 
Helmholtz supposed elements in the basilar mem- 
brane free to vibrate selectively to the rates of move- 
ment to which they were adapted, and by their 
vibration to excite the contiguous hair cells. The 
vibration rates to which these elements were sup- 
posed to be "tuned" increased progressively from 
the apex of the cochlea to the "lower" end of the 
membrane; thus the series of perceptible pitches 
corresponded to the series of hair cells and vibra- 
tory elements functionally connected with them.^ 

The latest investigations point to the excitation of 

^ For details on the Helmholtz Theory, see Howell, pp. 
376-379; M'Kendrick (Schafer), pp. 1171-1185. 



82 A SYSTEM OF PSYCHOLOGY 

the hair cells by the movements of the tectorial 
membrane: Beyond this, we are still in the realm 
of speculation. A number of theories have been 
elaborated in addition to that of Helmholtz, and 
two of them seem to be worthy of entertainment. 
These we may call briefly the telephone theory, 
and the extensity theory. 

The telephone theory antedates Helmholtz's, 
but has been recently revived in modified forms. 
Briefly, it holds that pitch is conditioned solely by 
the frequency of the nervous impulses transmitted 
to the brain — the pitch-characteristic being thus 
supposed to be a product of the brain cells. Now, 
whatever the exact mechanism for transforming the 
vibratory impulses transmitted to the inner ear into 
hair-cell stimulations, the apparatus highly sensi- 
tive to one rate will not be so sensitive to other rates. 
Hence the need for a series of such apparatus (which 
is furnished in the cochlear structures) that will 
give the maximal sensitivity to a great range of 
vibration rates. This is mechanically the most 
rational of all the theories; it also has the advan- 
tage of explaining the pathological phenomena, and 
many other details, on practically the same simple 
grounds as does the Helmholtz theory, while not 
open to the objections to the latter. 



SENSATION QUALITY 83 

The extensity theory is less happy mechanically, 
but more strictly in accord with the psychological 
facts. Moreover, it does not turn the whole matter 
of pitch over to unidentified brain activity, but puts 
it on a basis where auditory sensation is strictly 
comparable with other sensations. This theory 
holds that the frequency of the vibration deter- 
mines the length of the series of hair cells (measured 
from the vestibular end of the total series) stimu- 
lated by a given tone. The slower the vibration, 
the more cells stimulated. Below a certain rate, 
all the nerve endings are stimulated; above a cer- 
tain rate, none. 

So far as we can discover there is but one ele- 
mentary auditory quality. It is customary to speak 
of pitch as quality, but that is an unjustifiable use 
of the word, for the difference between red and 
blue is not at all of the same sort as the difference 
between a low and a high note, although physically 
they both correspond to a difference of vibration 
rate. 

It is true that as notes are sounded they differ in 
a respect other than pitch, which again is com- 
monly called quality. The note of the violin, when 
of the same pitch as the note of the flute, is readily 
distinguishable from it. Low and high notes of the 



84 A SYSTEM OF PSYCHOLOGY 

same instrument differ more or less in the same 
way. This difference is one of complexity and 
intensity of components, and in strict discourse 
should not be called qualitative. The best word 
available for this quasi-character of tones is timbre. 
The Helmholtz theory of audition makes pitch 
analogous to local sign of touch and sight. The 
"telephone theory'' might assign a strictly quali- 
tative nature to pitch, although acceptance of the 
theory does not necessarily commit one to the 
qualitative view. On purely psychological grounds, 
pitch is analogous to extensity of visual and tactual 
sensation and we shall, therefore, treat it further 
under the head of extensity. 

10. Cutaneous and Subcutaneous Sensations 

Scattered through the skin, and the tissues im- 
mediately beneath it, the mucus membrane, the 
peritoneum of the abdominal cavity, the tissues 
adjacent to the apposed joint-surfaces, and in the 
muscles, tendons, and bones themselves, there are 
numerous sensory nerve endings, of a wide range 
of complexity, which respond to mechanical stim- 
ulation and to temperature changes. The joint, 
muscle, and tendon endings we will discuss in the 
next section, treating here only those in and im- 



SENSATION QUALITY 85 

mediately beneath the superficial coverings and 
linings. 

The simplest of these organs are no more than 
slight knobs on the ends of nerve fibres, in contact 
with cells of the tissues in which they are placed. 
A development from the knob is a little disk, or 
concave plate, in contact with a cell as the cup with 
an acorn. In a third form, the nerve ending is be- 
tween two specialized cells. In higher forms there 
are several knobs, or platelets, on branches of the 
nerve fibre, or fibres, which are enclosed within 
special cells or structures. The most complicated 
organs contain networks or "skeins" of nerve fibres 
of great intricacy . 

As these differeiit sorts of nerve endings were dis- 
covered they were given the names of their dis- 
coverers. Thus there are "end-bulbs of Krause,'^ 
"Pacinian corpuscles," "plume-organs of Ruifini" 
and so on. As more types are discovered, and as 
they are found to form a series in increasing com- 
plexity, these names become of less importance 
except to the anatomist.^ 

The cortical centres for cutaneous sensation are 



^For dermal and sub-dermal structures and organs see 
Piersol; figs. 867 to 875, and 1146 to 1148; Quain, figs. 389 
to 398, 402, 403, 407, 408. 



86 A SYSTEM OF PSYCHOLOGY 

variously located by different physiologists. The 
most probable theory is that they are near the 
"motor zone/' on the anterior side of the fissure of 
Rolando.^ This statement holds also for the sim- 
ilar sensations from the mucus membrane, and 
from the subcutaneous tissues. For convenience, 
and in accordance with established custom, we will 
refer to these all as " cutaneous '' except where we 
make specific distinction. 

The qualities of cutaneous sensation are fairly dis- 
tinct. Touch, tickle, warmth, and cold, are easily 
discriminated. Pressure is possibly of a different 
quality from touch. Pain is commonly considered 
as a specific quality of sensation, but of that we will 
speak below. 

Touch is aroused by light mechanical stimulation 
of the skin (or of the mucus membrane, etc.). It 
may also be aroused by electrical stimulation, by 
radiant heat, or (on the mucus membrane) by the 
action of certain substances denoted as "astrin- 
gent." Tickle is aroused by a lighter stimulation, 
and pre-eminently if the stimulus is of the stroking 
sort. It is practically impossible to arouse tickle 
without in some degree arousing touch also, and 
light touches are very apt to give gargalic sensation 
^ Piersol, figs. 1041-1043. 



SENSATION QUALITY 87 

along with the tactual; nevertheless, the two sen- 
sation-qualities are so distinct that they are unmis- 
takably discriminated. They are also strongly 
distinguished in respect to intensity of stimulus and 
motor response. A very light stimulation will 
arouse a powerful tickle sensation, and the impulse 
to move the hand to the spot tickled, or to move the 
tickled member, is usually irresistible. The develop- 
ment of this strong reflex through the necessity 
of guarding against insects has often been conject- 
ured. If the stimulation is increased in intensity, 
the sensation of touch replaces that of tickle, and 
the sensation intensity is much reduced, as is also 
the strength of the reaction-impulse. 

The production of tickle sensation usually in- 
volves also the production of organic processes and 
sensations in addition to the specific reflex. This 
general bodily disturbance, which doubtless has its 
function in the acceleration and intensification of 
the reaction, is commonly known as tickle, or tick- 
lishness; but this we are not discussing here. We 
are referring to the quality of the superficial sensa- 
tion alone. 

Pressure, as we use the term (usage in regard to 
"touch'' and "pressure'' varies very much) is 
aroused from organs deeper than the skin; or at 



88 A SYSTEM OF PSYCHOLOGY 

least it is aroused by physical pressure heavier than 
is required to arouse touch. It may be of the 
same quality, nevertheless; inspection shows in it 
nothing certainly different from intense tactual 
sensation free from the gargalic; and common usage 
treats touch and pressure as one. 

Warmth and cold are distinct qualities, although 
dependent on variations in the same physical tem- 
perature continuum. In this respect they are perhaps 
analogous to touch and tickle. The conditions for 
the arousal of warmth and cold are complex, and 
as yet not well understood. When the skin has 
been maintained at a certain temperature for a 
short time it usually ceases to respond to that ther- 
mic condition with either rhigotic or thalpotic sen- 
sation. This temperature is, therefore, called the 
neutral point for that portion of the skin at that 
particular time. If now the skin is subjected to 
temperature conditions above this neutral point, the 
nerve endings are so stimulated that warmth sen- 
sations occur; conversely, if the skin is subjected 
to a temperature below the point of neutrality, pro 
tempore, cold is felt; the sensation persisting in 
either case until a new neutral point is established. 
There are, however, cases which this formulation 
does not seem to fit, and a formulation in terms 



SENSATION QUALITY 89 

of a temperature-zero has been attempted. When 
the temperature of the skin is above this zero (it is 
supposed) warmth sensations are aroused; when 
below, cold. This theory may be stated adequately 
as follows: When we feel cold (or warm) the tem- 
perature of the skin is below (or above) a temperature 
at which — under conditions otherwise the same — 
we would feel neither warmth nor cold. This may 
be true, but it doesnH seem to help much.^ 

As the temperature of the body varies in differ- 
ent regions, objects which feel warm to one part 

* Perhaps the safest hypothesis is that the nerve endings 
adjust themselves to a rate of heat-radiation from the skin, 
if that rate lies within a certain range, and is maintained for 
a certain length of time, so that they are not stimulated. If, 
now, the rate is suddenly changed, stimulation of the appro- 
priate end-organs takes place and continues until the organs 
adapt themselves to the new rate. If the change is made 
gradually the protective adaptation may take place with 
very little, or practically no, sensation as in the case of color 
adaptation. Thus, if the hand is placed in water which feels 
"neutral," and held still while the temperature of the water 
is slowly raised or lowered, the water may be heated or cooled 
to a point which would normally feel hot or cold to the hand, 
yet in this case no sensations be aroused. I have seen a pa- 
tient's hand which was kept in warm water for several hours 
for the treatment of an abscess. The water became slowly 
hotter, and so scalded the hand that the skin came off over the 
whole surface, yet the patient f oimd the water only comfort- 
ably hot. Frogs have been frozen stiff, or boiled to death, 
while making no efforts to escape or giving other signs of dis- 
comfort; the water. in which the animal was placed being 
changed in temperature very slowly. It is true that these 
last illustrations bear more specifically on the so-called pain 
sense; but see text. 



90 A SYSTEM OF PSYCHOLOGY 

mav feel cool to another. The cold and warmth 
processes may be aroused by agents other than 
temperature changes; pepper, for instance, arouses 
warmth. Or, if these "warm*^ substances do not 
directly excite the nerve endings, they at least lower 
the neutral point. 

It has been alleged that heat is a combination of 
the warmth and cold qualities, and certain experi- 
ments seem to support this view. The significance 
of the experimental results is, however, a matter of 
doubt, and there is as yet no suflBcient reason for 
considering "heat" as other than an intense and 
perhaps "painful" warmth sensation.^ 

Pain is often listed as a specific quality of sensa- 
tion. This usage arises in part from considera- 
tion of the topographic distribution of cutaneous 
sensation (see below) and in part from imperfect 
analysis. The use of the word pain in this connec- 
tion is due to a confusion of the pricking or stinging 
quality of the sensation aroused by the stick of a 
needle with the powerful unpleasantness which often 

^ The impulse to the interpretation of heat as warmth j)lus 
cold comes /doubtless, from certain analogies, between warmth 
and red, and cold and green. We usually term the reds 
"warm" colors, and greens " cold/' If heat were a combina- 
tion, either psychologically or physiologically, of warm and 
cold, it would be analogous to yellow. The next step would 
be to analogize touch to blue, and pain to white. 



SENSATION QUALITY 91 

characterizes such sensations. By sticking the hand 
with the needle carefully, so that the sensation is 
not unpleasant, the same quality can be aroused, 
and then seems to be no other than a small, intense 
heat sensation, chiefly distinguished from a true 
heat sensation by not being accompanied by sensa- 
tions of warmth (less intense heat) from adjacent 
localities and by being smaller than the heat ex- 
tensity. By these differences, and possibly by dif- 
ferences in the time relations — the rapidity of de- 
velopment and fading of sensations — we are usually 
able to distinguish the sensation from a heat stim- 
ulus, from that of a sticking or cutting stimulus. 
Sometimes, however, we are misled and may feel 
a prick as a burn, or vice versa. 

Itch is usually a combination of tickle with 
warmth or heat. Often the warmth has scattered 
points of relatively high intensity — prickling — which 
makes the itch highly unpleasant. Rubbing the 
itching areas relieves the situation by temporarily 
annulling the tickle. 

Ache, such as may be aroused by plunging the 
hands in ice- water, is not a cutaneous sensation, and 
is capable of being aroused generally throughout the 
organism. We shall speak of it under organic sen- 
sation. 



92 A SYSTEM OF PSYCHOLOGY 

Not all of the dermal sensations are to be aroused 
readily from any point of the skin. If you move a 
cool or warm metal stylus lightly and carefully over 
the skin, you will find that only at certain points is 
the thalpotic or rhigotic sensation produced, unless 
between these points the stylus is allowed to rest 
long enough for heat to be transmitted laterally. 
You may mark these points where the sensation 
appears directly with small ink spots (one color for 
the spot stimulated by the warm stylus and another 
for that stimulated by the cold) ; then you may test 
for "pressure points" with a thin bristle, and "pain 
points" with a fine needle. You will find that many 
points in the skin may be penetrated painlessly, and 
on many the pressure of the bristle will not be felt, 
if the bristle is not too stiff, You make a chart on 
the skin of the points which are sensitive, and if the 
marks are made with indelible ink you may find 
that on following days the same points will respond, 
and the ones which did not respond continue in- 
sensitive, if the degree of stimulation is the same. 

A great deal has been made of this topographical 
distribution of sensation, since it was discovered, 
thirty years ago. It was at first supposed that the 
points indicated the locations of specific end-or- 
gans, and pieces of skin have been cut out and sub- 



SENSATION QUALITY 93 

jected to microscopic examination in the hopes of 
determining these organs, but without success. The 
permanence of the sensory points has been doubted 
by many investigators from the first, and it has at 
last been pretty well established that we have not 
to do with points, but with large areas, and that the 
points of maximal sensitivity within these areas 
vary considerably from day to day. The error of 
the earlier investigators was in marking the points 
on the skin, thus prejudicing their succeeding tests 
on the same areas. 

The latest physiological investigations indicate 
that there are three sorts of cutaneous and subcu- 
taneous sensibility from the physiological point of 
view. These are: (1) Deep sensibility to heavy 
pressure and to movement of the tissues, as when 
a member is flexed. (2) Protopathic sensibility, 
"pain,^' heat, and cold; heat stimulated by temper- 
atures above 45° C. and cold by temperatures be- 
low 20° C. (assuming the neutral point to be about 
37°). (3) Epicritic sensibility, touch and tickle and 
warmth and coolness; warmth and coolness pro- 
duced by temperatures lying between the neutral 
point and 45° and 20° respectively. If certain sen- 
sory nerves are severed, areas supplied by them 
lose sensations of the second kind, but the first and 



94 A SYSTEM OF PSYCHOLOGY 

third are unaffected. Severance of certain other 
nerves destroys sensitiveness of the third sort, with- 
out affecting the first and second. And, finally, 
severance of certain "motor"' nerves destroys sensi- 
tiveness of the first sort only. 

These facts indicate that there are two sets of 
nerve endings giving warmth and cold sensations, 
but under different conditions — the one set respond- 
ing to slight stimulations, and capable of only a 
feeble action, the other set requiring a much greater 
stimulus, but capable of intense response. These 
last-mentioned organs may also be excited by me- 
chanical stimulations, as pressure or cutting. There 
are perhaps eight types of nerve endings, according 
to their functions, as follows: tickle, touch, weak 
warmth, weak cold, heat and "sharp pain,'' cold 
(strong), deep pressure, and "dull pain" or ache. 
Or perhaps two sensory processes may be the func- 
tions of one organ. 

In certain diseases which affect the spinal cord 
and roots of the nerves, we find interesting dissocia- 
tions of sensation, differing from those just de- 
scribed, where nerves are severed at some distance 
from the spine. In the degeneration of the spinal 
cord known as syringo-myelia, all sensations of cold, 
warmth, and "sharp pain" are lost from large areas 



SENSATION QUALITY 95 

of the body without affecting touch or pressure. 
In other diseases touch alone may disappear/ and 
in other conditions touch and cold are lost, but not 
warmth and heat. In some instances the sensibility 
of the hairs alone has been lost. 

II. Kinaesthetic and Coenaesthetic Sensation 
The muscular and visceral sensations furnish us 
with another striking illustration of the difficulties 
which beset psychological analysis. The quali- 
tative distinctions within these classes are scientifi- 
cally no less important than in the other sensory 
groups, yet the distinctions have to go unmade. In 
the case of the muscular sensations, we attend so 
predominantly to what the sensations signify — to 
the ideas they arouse— that we are not able to notice 
adequately the sensations themselves. Perhaps the 
ability to attend analytically to these sensations 
would unfit the patient for the simplest routine of 
life, so important is it that we attend to what they 
mean, rather than what they are. 

Under the head of muscular sensation we include 
all those which result directly from muscular move- 

^ In the eases reported, however, it is not certain whether 
deep pressure did not go, too. Tickle undoubtedly was lost, 
also, but no report is made of that, it being usually assiuned 
by the clinician to be a form of touch. 



96 A SYSTEM OF PSYCHOLOGY 

ment, excepting those already described as dermal 
and subdermal, although touch, for example, is 
aroused when the arm is flexed or extended.^ We 
include, therefore, sensations produced by excita- 
tion of endings in the muscles,^ in the tendons, and 
in tissues near the joints. When I raise my arm, 
the contraction of the muscles excites the platelets 
which are in contact with its fibres, the change of 
tension of the tendons probably excites endings 
therein, and the movements of the head of the hu- 
merus in the shoulder socket, and of the apposed 
surfaces in the elbow joint, excite endings in the tis- 
sues surrounding them; and the sensation-complex 
resulting from all these excitations — or in the last 
resort, from their cortical effects — I call the "feel- 
ing of raising my arm/^ If the muscular contrac- 
tion occurs, but the arm is held by external force, 
the details of stimulation in muscle and joint are 
somewhat different; the muscle does not change its 
shape so much, and certain nerve terminals are 
doubtless less stimulated, others more stimulated, 
than if the movement had occurred, the articular 



^ For sensory endings in the muscles, see Piersol, fig. 876. 

2 It is possible that the deep pressure already mentioned is 
really a sensation from nerve endings in the muscles, stirred 
by the pressure, and ought to be classed as muscular sensa- 
tion; I am at present inclined to that opinion. 



SENSATION QUALITY 97 

surfaces are subjected to pressure, not to friction. 
This sort of stimulation arouses, through its brain 
effect, a sensation-complex which we call the " feel- 
ing of effort," or of "weight." 

Whether different qualities are produced from the 
joints under different conditions, and whether the 
relaxation of a muscle arouses a sensation of quality 
different from that excited by contraction, we can- 
not say. The differences on which our judgments 
depend may be all the results of combinations of a 
single joint-quality and a single muscle-quality, the 
extensities and intensities varying. 

It is difficult to analyze the organic sensations, 
not because we do not attend directly to them, but 
because there is no experimental way of varying 
them, and they occur normally in such regular com- 
plexes that the noting of elements is almost im- 
possible. You must remember that if we saw pur- 
ple only in the hue called " magenta," and never in 
the hues nearer the spectral colors, we should proba- 
bly never guess that it is red jplus blue. So it is with 
nausea, lassitude, and such organic contents; they 
may be complexes of elements which occur in dif- 
ferent combinations, but so regularly that they 
might as well be elements, so far as our experience 
goes. We are in much the same position here that 



98 A SYSTEM OF PSYCHOLOGY 

we are as regards odors. Whether the elements are 
many or few, we are unable to tell. 

The organic sensations seem not to be aroused by 
direct action of external stimulation, and those tis- 
sues which possess this form of sensibihty alone (as, 
for instance, the peritoneum covering the intestines, 
and the intestines themselves), may be pinched, 
cut, burned, or otherwise maltreated, without the 
production of any sensation. Even powerful intes- 
tinal contractions, artificially brought about, pro- 
duce no effect sensationally. Yet, under certain 
conditions, which may, for all we know, be chemical 
stimulations within the tissues, or changes in the 
channel of flow of the nervous currents originating 
in these tissues, decided sensational results are pro- 
duced; witness the juvenile belly-ache.^ 

One sensation-quality which does not quite come 
under the above description, but which ought per- 
haps to be included under coensesthesis, is dizziness, 
or vertigo. This is produced either directly or 
indirectly by the stimulation of the nerve endings 
in the semicircular canals. These canals, which 
lie approximately in three planes, at right angles to 



^ There is a theory that belly-ache is due to the irritation 
of the abdominal peritoneum, which is sensitive to pressure, 
cutting, etc., giving only a ''painful" sensation. 



SENSATION QUALITY 99 

each other, and so are sensitive to rotation in any 
direction, are supplied by a branch of the same 
nerve which supplies the cochlea, but the sensa- 
tions are by no means auditory. Pathological irri- 
tation of the semicircular canals produces sympto- 
matic dizziness, and if the canals are completely 
destroyed the patient can no longer be made dizzy. 
Dizziness is associated with various nervous phe- 
nomena, notably the rhythmic eye movements known 
as nystagmus (whirling until one is dizzy will pro- 
duce these movements), and can be produced in 
so many ways (eye disease, indigestion, mental 
shock, are some of the ways) that any conclusion as 
to the exact function of the semicircular canals is 
at present impossible. 

The "dark-brown taste ^' to which we have re- 
ferred earlier is perhaps due to excitation of nerve 
endings in the mucus membrane by substances 
produced directly or indirectly as a result of ab- 
normal chemical changes in the alimentary canal. 
In the general organic feelings of well-being, de- 
jection, placidity, etc., as well as in more specific 
emotional content, it is possible that an important 
causal factor is stimulation by chemical substances 
(hormones) secreted by the various ductless glands, 
and poured by them into the blood. 



100 A SYSTEM OF PSYCHOLOGY 

The painful sensation known as ache is apparently 
the function of various tissues deeper than the skin 
and mucus membrane. It is a true coenaesthetic 
sensation, although seemingly allied to intense cold. 
This suggestion of cold is doubtless a matter of 
association, cold being a common cause of ache. 



CHAPTER V 

THRESHOLDS OF CONSCIOUSNESS 
I. Stimulus-Thresholds 

In order that a stimulus may produce a sensation 
it must satisfy certain limiting conditions called 
stimulus-thresholds. These conditions, which are 
strictly physical, are matters of (a) wave length or 
molecular character, (6) intensity or amount of en- 
ergy per unit of time, and (c) duration of action of 
the stimulus and extent of area affected by it. All 
these conditions are capable of being expressed as 
magnitudes. 

Of the first type we have given one illustration 
already, in speaking of odors, which must have the 
molecular weight of HCN at least. Probably sim- 
ilar determinations may be made for gustable sub- 
stances. Light-waves must have a length of not 
greater than circa seventy-five hundred-thousandths 
of a millimeter (.00075 mm.) and not less than 
thirty-eight hundred-thousandths (.00038 mm.) in 

order to arouse visual sensation. The longest air 

101 



102 A SYSTEM OF PSYCHOLOGY 

vibration which will arouse a sensation of tone 
is about twelve meters, and the shortest about 
one-half of a millimeter. These magnitudes are 
thresholds. 

If we consider ether-vibrations of suflBcient energy 
falling on a normal retina, commencing with waves 
too long to be visible and steadily decreasing in 
length, we can conceive that when a certain wave 
length is reached a sensation of light will occur; it 
will "enter the mind" or "enter consciousness'' at 
that point. This point at which the sensation 
"steps in'' is accordingly dubbed the threshold. 
In the cases of sound and light there are two thresh- 
olds; you can approach the limits of sensibility 
from either direction; and the same may be true of 
smell. There may be gases which are odorless be- 
cause their molecular weights are too great. 

These thresholds are sometimes — and incorrectly 
— called qualitative. There is no such thing as a 
qualitative threshold. Clearness and accuracy can 
be attained by referring to the auditory wave-fre- 
quency thresholds, the visual wave-length thresh- 
olds, etc. 

The second sort of thresholds occur in the series 
of intensities of stimulations, and this sort of thresh- 
old is always meant by the term when not expressly 



THRESHOLDS OF CONSCIOUSNESS 103 

qualified to signify otherwise. These thresholds 
may be referred to as the acoustical intensity-thresh- 
old, the optical intensity-threshold, etc. 

The acoustical and optical intensity-thresholds 
are theoretically measurable as certain amplitudes 
of waves of a given length (see next chapter), but 
practically they are measured in a much more 
primitive way. The acoustical threshold is ex- 
pressed as the distance through which a given ball 
must be dropped on a given plate or block, at a 
given distance from the ear, in order to produce an 
auditory sensation. The optical threshold is usu- 
ally determined by finding the proportion in which 
a given beam of light may be reduced, and yet 
arouse a visual sensation. As might be expected, 
such determinations are not very satisfactory. 

The osmical threshold is accurately determined 
by finding the least amount of a given substance 
which, infused in a unit quantity of dry air, will 
produce the appropriate sensation under the best 
conditions of inhalation. So the geusical threshold 
is determined by finding the least amount of sub- 
stance which, dissolved in a unit quantity of dis- 
tilled water, will arouse taste sensations. 

The haptic threshold is determined by laying 
weights on the skin or by pressing it with delicate 



104 A SYSTEM OF PSYCHOLOGY 

springs of metal or hair, giving known amounts 
of pressure. The hapto-algetic threshold may be 
similarly measured by finding the least pressure on 
a given area producing "pain/' The intensity- 
threshold for warmth and cold cannot be meas- 
ured adequately by any simple method. 

The stimulus acting on any organ must act for a 
certain length of time before a sensation is produced, 
and, if the intensity is low, a duration may be found 
which will allow no sensation to be raised into con- 
sciousness. A light, intense enough to be clearly 
seen under ordinary conditions, may remain invisible 
when allowed to fall on the retina for only a few 
thousandths of a second. Conceivably, this dura- 
tion-threshold is only an aspect of the fundamen- 
tal intensity-threshold; for the energy applied in 
the brief time measured by the duration-threshold 
is just sufficient to raise the neural process to the 
point at which a sensation is produced. 

The area- thresh old of stimulation, which is im- 
portant only in vision, is doubtless also of deriva- 
tive nature, the energy being distributed over an 
area wider than that mathematically correspond- 
ing to the external object or its projection on the 
organ. 



THRESHOLDS OF CONSCIOUSNESS 105 

2. Stimulus Difference Thresholds 
Two stimuli may be different in intensity, in 
wave length, in duration, or in some other feature, 
and yet there may be no difference noticeable in 
the sensations corresponding to the stimuli. So 
far, it is an open question whether this failure to 
observe a difference in the given respect means that 
the sensations are really the same in that respect, 
or whether they are necessarily different (assum- 
ing that the conditions of the organ and environ- 
ment are equivalent, except in respect to the differ- 
ence of stimulus under consideration). The fact 
remains that a certain measurable difference in 
stimuli is necessary in order that a corresponding 
difference may be perceived in sensation.^ The 
magnitude of this required difference is called the 
difference threshold. The difference threshold is 
usually expressed as the increment or decrement 
which must be made to any stimulus before the in- 
creased or decreased stimulus produces a sensation 
differing in the corresponding way from the sensa- 
tion produced by the original or "standard stimu- 
lus." 



^ This statement is subject to the consideration of the 
"Constant Error. '^ See next section. 



106 A SYSTEM OF PSYCHOLOGY 

3. Other Thresholds 

There are other thresholds which we have not 
considered above. Note that we have so far 
been deaHng with the stimulus-threshold, or the 
stimulus difference threshold. They are some- 
times called "sensation-thresholds/' but the other 
designation is the accurate one. They are always 
determined by the measurement of stimuli which 
produce a specified effect before consciousness. 
There are other thresholds which are not the 
measurements of stimuli at all. 

We may determine, for example, the least time 
interval perceptible as such; or the least space in- 
terval in touch or vision. Or we may determine the 
difference threshold for time intervals. These mat- 
ters are not relevant here except to forestall the sup- 
position that all thresholds are stimulus-thresholds. 

4. The Constant Error 

Suppose I wish to find the stimulus difference 
threshold for intensity (which for brevity we may 
call the I. D. T.), for a pressure of twenty-five 
grams on the centre of the palm of the hand. Ob- 
viously, the general method of procedure must be to 
place on the selected spot of the patient's hand 



THRESHOLDS OF CONSCIOUSNESS 107 

a weight of twenty-five grams, alternating with 
weights sHghtly greater and shghtly less, until we find 
the least weight which is felt as heavier, and the 
greatest which is felt as lighter, than the twenty-five- 
gram ("Standard") weight. The elaborate tech- 
nic and many precautions necessary to make our 
results significant, we need not describe here, but 
one feature of the experiment is of present impor- 
tance: If the "Standard'^ weight is given first in 
each case, and the second weight ("Variable") is 
varied appreciably, the patient (who, of course, is 
not allowed to see the hand and weights, and is not 
informed as to their actual weight values), will in 
very many cases declare the "Variable" heavier 
or lighter than the "Standard", when the two are 
exactly equal. You may find at the end of your 
experiment, for example, that the weight which is 
on the average just perceptibly heavier than the 
"Standard," when the "Standard" is given first, is 
actually lighter than the "Standard"! But this 
disconcerting result is not at all erroneous or 
troublesome. If you make an equal number of 
experiments with the "Variable" first and the 
"Standard" last, you may find the results the con- 
verse of the first set — the just perceptibly lighter 
weight being now heavier than the "Standard." 



108 A SYSTEM OF PSYCHOLOGY 

In short, your results include two factors; the 
I. D. T., and the constant error (C. E.) due to the 
order of the weights. The second of two weights 
is not judged under the same conditions as is the 
first, and vice versa. You must always make ex- 
periments in both time orders (S-V and V-S), and 
by comparing the results in the two cases determine 
the C. E. of time order, before you can determine 
the approximate D. T. 

Constant errors, due to all sorts of factors, con- 
tribute to the complexity of the problems of experi- 
mental psychology, and in many cases the determi- 
nation of the magnitude of the C. E. under definite 
conditions becomes a method of solving important 
problems. 



CHAPTER VI 

SENSATION-INTENSITY 
I. Intensity of Sensation and Intensity of Stimulus 

As we have already implied, the intensity of sen- 
sation depends in general on the intensity of the 
process in the end-organ and brain, which in turn 
depends in part on the intensity of the physical 
stimulus. There are, therefore, two relations to be 
considered: (1) the relation between the stimulus 
and the nervous process, and (2) the relation be- 
tween the nervous process and the sensation. Con- 
cerning each of these relations we have practically 
nothing but the bare fact that, ceteris paribus, an 
increase in the intensity of one is connected with 
an increase in the intensity of the others. 

The condition of the sense-organ has an important 
influence on the intensity of the sensation result- 
ing from a given stimulation : fatigue and adaptation 
can modify the result immensely. Thus, the light 
sensation aroused by light striking the dark-adapted 
eye may be very much brighter than the sensation 

aroused by a light many times more intense acting 

109 



110 A SYSTEM OF PSYCHOLOGY 

on the light-adapted eye. These facts do not offer 
any serious logical obstacle to the formulation of 
statements of intensity relation, as all such are sim- 
ply required to specify that the relation holds only 
for a uniform condition of the sense-organ and 
nervous connections; but they introduce serious 
practical diflBculties, because it is not always possi- 
ble to ascertain whether the condition of an organ 
is uniform during any given period of experimenta- 
tion. 

The diflficulty of the discovery of definite inten- 
sity relationships of sensation and stimulus is in- 
creased by the difficulty of estimation. Direct meas- 
urement of sensation-intensities is impossible. We 
can only compare one sensation with another, and 
determine which of the two is more intense. And 
this determination is strictly relative. The apparent 
intensity of a sensation is affected by other sensa- 
tions, aside from any change in the actual intensity 
of the sensation. For instance: a candle burning 
near a coal-oil lamp seems dimmer than the same 
candle burning beside the flame of a minute gas- 
jet; yet, if the experiment is performed in moder- 
ate daylight, the candle flame is practically as 
bright sensationally in the one case as in the other. 
When the time factor enters, and sensations pres- 



SENSATION-INTENSITY 111 

ent are compared with past sensations, the relativity 
of the judgment of comparison becomes greater. 
But even when the time factor is not present, 
the comparison of sensations of any sense is rel- 
ative. 

Taking into account the relativity of sensations 
and the relativity of the estimation of sensations, 
we find diflBculties enough to account for the fact 
that no laws of the quantitative relation of stimulus- 
intensity to sensation-intensity are discoverable at 
present. The nearest approach to a law of this kind 
is "Weber's Law," which deals with the intensity 
difference threshold only. 

2. Weber's Law 

If we express the intensity D. T. as a ratio of 
the just perceptible increment (or decrement) to 
the Standard, we may state Weber's Law in the 
following terms: The I. D. T. for different values 
of a standard stimulus varying in intensity only is 
practically constant if the general condition of con- 
sciousness remains the same. This law holds, how- 
ever, only for mean ranges of intensity; for feeble 
or very high intensities it is invalid. 

Weber's Law may be expressed less technically, 
but yet accurately, as follows: The ratio of the 



112 A SYSTEM OF PSYCHOLOGY 

intensity of a standard stimulus to the just percepti- 
ble increment in intensity is the same as the ratio 
of the intensity of any other standard to its just 
perceptible increment (or decrement), provided 
the sensations aroused by the two standards differ 
only in intensity, and provided that the general 
mental and physical condition of the patient is the 
same in the tests with the different standards. There 
will be in any case a minimum standard and a 
maximum standard, below which and above which, 
respectively, the equality will not hold. 

As a concrete example of the uniformity described 
by Weber^s Law, we may give the following. If the 
pressure of fifty grammes on the finger needs to be 
increased to fifty-one grammes in order that the in- 
crease may be noted, the pressure of one hundred 
grammes will need to be increased to one hunderd 
and two. In other words, the I. D. T. at fifty 
grammes (^) is the same as the I. D. T. at one 
hundred grammes (y^)- Above perhaps four hun- 
dred grammes, and below perhaps ten grammes, the 
ratio will be somewhat different. 

The provisions to which we have given place in 
the formulations are exceedingly important. Among 
other cases in which these provisions preclude our 
expecting the I. D. T/s to be equal, the following 



SENSATION-INTENSITY 113 

may be noted: (1) Different senses, or different 
qualities; thus, we would not expect to find the 
I. D. T. for sugar the same as that for blue light, 
or even for salt. (2) Different individuals. (3) 
Different portions of the sense-organ, as the centre 
and periphery of the retina. (4) Different exten- 
sities or durations of sensation. (5) Different con- 
ditions of the patient, as rested and fatigued. In 
addition, we do not find a constant D. T. for any 
other character than intensity. Weber's Law has 
no bearing on the D. T. for color change (wave 
length), or pitch, or duration. It applies to inten- 
sity only. 

Weber's Law was given its name in honor of 
E. H. Weber, who first discovered the facts which it 
describes. The first formulation, and the appli- 
cation of the name, were the work of G. T. Fech- 
ner, who attempted to give the law an application 
to stimulus differences greater than those just per- 
ceptible, and to turn it into a statement of the re- 
lation of stimulus-intensity to sensation-intensity. 
Fechner's attempt, based on the assumption that all 
just-perceptible differences in sensation are equal, 
resulted in "Fechner's Law," and "Fechner's 
Formula," which expressed the relation as a logarith- 
mic equation. The discussions, controversies, and 



114 A SYSTEM OF PSYCHOLOGY 

investigations consequent on this formulation con- 
stitute the subject sometimes called psycho-physics. 
Fortunately for the student, the whole matter is 
chiefly of historical importance, and may be safely 
ignored in an elementary course/ 

3. The Comparison of Intensity Differences 

The determination of the just perceptible differ- 
ence involves an equating of intensities. In order 
to find what intensities seem equal to a given inten- 
sity, we must find the greatest which seems less and 
the least which seems greater; conversely, in de- 
termining these thresholds, we have substantially 
determined the intensity equivalents. In addition 
to finding equal-seeming intensities of sensation we 
may also compare differences of intensity with re- 
gard to their equality or non-equality; but we find 
that the results of these judgments are less uniform 
than those of mere intensity. 

If we find two sensations, Si and S2, which ap- 

^ The analytically inclined student may be disturbed by 
the careless way in which we speak of the discriminating of 
differences of stimuli, instead of the discriminating of differ- 
ences of sensation corresponding to certain differences of stim- 
uli. We trust, however, that the discussion gains in simplic- 
ity without losing in clearness by that looseness. 

For an adequate discussion of Fechner's addition to Weber, 
see James, Principles of Psychology, vol. I, chap. XIII, pp. 
533-549. 



SENSATION-INTENSITY 115 

pear exactly as different in intensity as two other 
sensations, S3 and S4, we might expect to find on the 
analogy of Weber's Law, that the stimuli of the 
first pair have the same intensity-ratio as the stimuli 
of the second pair. Letting the intensity of the 
stimulus be represented by R, the relation in ques- 
tion may be expressed, Ri/R2 = R3/R4. This rela- 
tion, which is demanded by Fechner's Formula, 
is actually found to hold in many cases. In other 
cases, however, the relation has been found to be 
more nearly that of equality of stimulus differences; 
Ri— R2 = Rs — R4, and this divergence has given rise 
to some acrimonious controversy over the " correct- 
ness'' of the one result or the other. As a matter 
of fact, both are correct. Some individuals will 
rather uniformly select "equahties" of the first 
type, and other individuals will select equalities of 
the second type. Certain individuals will select 
neither type of equality, and still others will select 
both} 

^ In extensive experiments on nearly sixty persons, using 
the same apparatus and same conditions throughout, I have 
found that in selecting a light-brightness or weight-intensity 
which seemed midway between two standard light or pressure 
intensities, the persons fell into four classes: (1) Those who 
selected the geometrical mean; (2) those who selected the 
arithmetical mean; (3) those who selected a mean which was 
the arithmetical mean of the geometrical and arithmetical 
mean; (4) those who selected approximately the harmonic 



116 A SYSTEM OF PSYCHOLOGY 

4. The Relativity of Sensation 

The relativity of sensation-intensity and inten- 
sity-differences; their variability, that is, according 
to the various conditions mentioned in the preced- 
ing sections, may account for the apparent ^'^ rela- 
tivity" of sensation-quality, w^hich is usually in- 
cluded by specification or implication in references 
to the " relativity of sensation/' It is often implied 
that the quality of a sensation is not determined by 
a definite stimulus acting on a corresponding ner- 
vous mechanism, but by this action in conjunction 
with all the other nervous and mental activities. 
Color contrast, and all the other conditions in which 
now this sensation, now that, are gotten from the 
same stimulus under different conditions, are cited 
in support of this view. These phenomena may 
not be due to qualitative variability at all, but sim- 
ply to the variability of intensity. 

A qualitative change in a sense-content may be 
one of three things. (1) It may be a change in the 
intensity or intensities of one or more of the quali- 

mean. Some of the persons were too irregular to be fairly 
classified at all, a few alternated between two types, and one 
person insisted on selecting two means, approximately the 
arithmetical and geometrical, which he insisted were both 
good, although not ''of the same sort." 



SENSATION-INTENSITY 117 

tative elements present in the content. (2) It may 
be the addition of a qualitative element, or of 
qualitative elements not previously present. (3) It 
may be a simulation, due to a direction of the atten- 
tion more strongly or less strongly to certain ele- 
ments. 

A sensation of pure red (if such is obtainable) 
may become more intense, or less intense, and may 
completely disappear; but, so long as it remains, it 
can be nothing but red. The same stimulus which 
now arouses pure red may, in a different condition 
of the eye, arouse some blue also; in which case the 
result is purplish. So daylight, which ''normally^' 
excites the three colors in such proportions of in- 
tensity that "white'^ results, may, if the eye is 
adapted to purple light, excite the green process 
with unusual intensity; hence, the green after-image. 
Distilled water does not ordinarily excite the taste- 
buds, and hence there is no gustatory sensation; 
but by the previous action of some drug the nerve 
endings may be made sensitive to the effect of the 
water; this is, in effect, the lowering of the stimulus- 
threshold. 



118 A SYSTEM OF PSYCHOLOGY 

5. Beats 

An important phenomenon of intensity in the 
auditory realm is that of beats. Beats are periodic 
fluctuations in the intensity of a sound, commonly 
arising when the stimulus (air-waves) is composed 
of vibrations from two separate sources, as two 
tuning-forks, or pipes, or strings, giving notes of 
proper pitches. Two sources of sound will give 
rise to beats if (1) the note of one is less than (circa) 
thirty vibrations per second faster than the other, 
or (2) when twice the rate of the lower is less than 
thirty vibrations faster or slower than the other. 
These beats are called beats of the first and second 
orders respectively. Beats of the third and higher 
orders exist theoretically, but are so weak as to be 
practically negligible. For the physical theory of 
the interference of the sound-waves, which produces 
the alternate maxima and minima corresponding 
to the beats in sensation, the student may refer to 
any good treatise on sound, or on general physics. 

A single source of sound, as, e. g., sl bell, may pro- 
duce beats through the interference of the partial 
tones contained in its note. It is this which gives the 
tremulous character to the sound of a bell. Alter- 
nate reinforcement and diminution of the intensity 



SENSATION-INTENSITY 119 

of a single note may be produced also by various 
extrinsic means. Tune a bottle to the note of a 
tuning-fork by pouring in water to the right height, 
and then rotate the fork, holding it horizontally over 
the mouth of the bottle: the beats thus produced 
are of the same character as those produced by two 
forks sounding together. The vibrato or tremolo 
of the human voice, which is an effective embellish- 
ment when used sparingly, and which mediocre 
singers employ without reason or mercy, is in some 
cases purely a matter of intensity-variation, i. e,, 
beats; in other cases (in most cases, in fact) it is 
partly a matter of pitch changes. 



CHAPTER VII 

PROTENSITY AND EXTENSITY OF SENSATION 
I. The Duration-Character 

The duration or protensity of a sensation is to be 
discriminated from the duration of the experience, 
and from the duration of the stimukis. A stimulus 
acting one second may produce a sensation lasting 
less than a second or more than a second. The 
sensation may not be experienced during a certain 
period of its existence; perhaps it may not be ex- 
perienced at any time; at least there are sensations 
which are unnoticed during a part or the whole of 
their existences. We cannot say with certainty that 
any sensation is experienced from beginning to end; 
perhaps all sensations have unexperienced phases. 
Even if we should admit, as certain metaphysicians 
would have us do, that the duration of the sensation 
and the duration of the experience of the sensation 
are equal and coterminous, we should still be obliged 
to hold that the duration of the one is logically dis- 
tinct from the duration of the other, for the duration 

which is characteristic of the sensation is actually 

120 



PROTENSITY AND EXTENSITY 121 

experienced along with the other characters (quality, 
intensity, etc.). In other words, the duration ex- 
perienced is not the same thing as the experience of 
the duration. 

The protensity or duration of the sensation as di- 
rectly experienced is distinguished from the duration 
as measured by its relation to series of other events, 
whether these events are other sensations directly 
experienced (as in the immediate estimate of time) 
or whether they are members of an ideal series 
based on mathematical subdivisions of the parallel 
of latitude (minutes and seconds).^ 

It is the duration of sensation as an experienced 
fact to which we refer in speaking of the protensity 
or duration-character. A sensation without it could 
never be brought into the time relation, and time, as 
we experience it, could not exist apart from sensa- 
tions. Time, however, involves more than sensa- 
tion-duration, as we will see later. 

The direct comparison of two sensation-durations 
is much more diflBcult than the comparison of in- 
tensities. In the first place, it is impossible to ex- 

^ This mathematical relation of sensation-duration to a 
standard time series is often loosely designated the " duration 
of sensation " as distinguished from the '' experience of the 
duration," the last name being applied uncritically to the 
duration-character of the sensation, the estimated duration, 
and the experience of these. 



122 A SYSTEM OF PSYCHOLOGY 

elude a multitude of other sensations (bodily, etc.) 
which insist on taking a part in the comparison. 
In the second place, since in most cases the dura- 
tions compared must be in succession, the memory 
factor becomes especially disturbing. For these 
reasons, very little has actually been accomplished 
in the investigation of the difference-sensibility for 
protensity, although there has been a great deal of 
experimentation in the general field of time-content. 

2. Extensity 

Extensity is related to space as protensity is to 
time. In each case the sensation-character is so 
intimately built up into the complex that it is diffi- 
cult to analyze it out; but the analysis is the less 
difficult in the case of extensity. 

Extensity can best be demonstrated in the dermal 
sense. Provide yourself with a small cork stopper 
and a small wooden rod with a blunt, very slightly 
rounded point. Touch yourwrist or lower arm alter- 
nately with the rod and with the cork, avoiding hairs 
and veins, and pressing just hard enough to arouse 
touch sensations. Notice that the touches have 
different '* bigness'^ although neither has any space- 
form; that is, you cannot discriminate any parts in 
either; you cannot discriminate edge from middle. 



PROTENSITY AND EXTENSITY 123 

or one side from the other. The difference which 
you observe is one of extensity. In a corresponding 
way, extensity-differences may be demonstrated in 
the visual field. 

Extensity-differences depend physiologically on 
differences in the number of nerve endings stimu- 
lated. In general, the more nerve endings stimu- 
lated, the more extensive the sensation, but we can- 
not expect to find any definite relation of number 
to extensity which would hold for different parts of 
the organism, or even for different parts of a sense 
organ. Extensity-differences occur wherever there 
are nerve endings capable of stimulation in different 
numbers, as in the senses of vision, touch, warmth, 
cold, and bodily feeling.^ 

In the case of auditory sensations, the extensity, 
if it exists, is probably that which we commonly 

^ The difference in volume between different aches, for 
example, is often noticed. In smelling, it is possible that 
practically the whole group of nerve endings which are ca- 
pable of responding to a given odor are stimulated every time 
the odor is aroused, as we find no pronounced differences of 
extensity with any one odor. Whether different odors have 
different extensities we cannot say conclusively. The sen- 
sations of smell, nevertheless, have extensity, even though 
differences therein are obscure; it is the apparent (or real) 
sameness or the practical unimportance of differences, which 
makes us overlook the character in olfactory experience. Yet 
we ought not to say even that it is practically unimportant, 
until we are certain that it plays no part in the puzzHng com- 
position of odors. 



124 A SYSTEM OF PSYCHOLOGY 

call "pitch. The nerve endings (the hair-cells) in the 
cochlea of the ear form a linear series (or multiple 
linear series) running the length of the basilar mem- 
brane, and it is probable that high notes (rapid vi- 
brations) stimulate only the cells situated at the 
end nearer the middle ear; lower notes (slower vi- 
brations) stimulating a larger number. It is well 
known that the destruction of the cochlear nerve 
endings nearest the middle ear (at the basal extrem- 
ity of the basilar membrane) destroys the sensitiv- 
ity of the ear for high tones, but not for low ones, 
and this agrees well with the extensity theory, but 
with no other except that of Helmholtz. 

The introspective fact that the difference between 
low and high tones seems like the difference of ex- 
tensity of other sensations; the fact that the sound- 
ing of a low tone obscures a feeble high tone, while 
the sounding of a high tone does not obscure a 
feeble low tone; the fact that the highest audible 
tone, no matter what its actual pitch, always seems 
'* approximating zero," that is, having no conceiv- 
able terms beyond it in the pitch series; these and 
other facts point to the correctness of the pitch-ex- 
tensity theory. 

Pitch is no more noticed habitually as a mere 
sensation-character than are extensities of other 



PROTENSITY AND EXTENSITY 125 

sensations. We do not weave it into a space system, 
probably because of the lack of muscular adjust- 
ments for that function, but we do, nevertheless, or- 
ganize the different extensities in the usual mathe- 
matical way. One result of the organization is the 
musical scale, and we normally perceive tones in 
the scale relation, although usually not with mathe- 
matical exactness. Exactness is attainable for 
theoretical purposes, just as exact space measure- 
ments are possible in spite of the fact that our 
ordinary estimations of space "by eye^^ are mere 
approximations to accuracy. 

3. Overtones and the Musical Scale 

The method in which the diatonic scale which we 
use (in theory) at present, and the modifications of 
it employed in musical practice, were developed, is 
an interesting and important chapter in the psychol- 
ogy of auditory sensation, but a chapter which can 
only be sketched at present. The scale has de- 
veloped through the need of conforming to the 
natural series of overtones or partial tones (see be- 
low), the advantage of avoiding beats, and the 
simplicity of wood-wind instruments with regularly 
spaced finger-holes (primitive flutes), these instru- 
ments giving scales which are " near '^-dia tonic. 



126 A SYSTEM OF PSYCHOLOGY 

Overtones, or partials, are tones that sound along 
with the proper or fundamental tone of a source of 
sound; or, rather, they are components in the total 
note, which are higher in pitch than the principal 
component or fundamental. Partials of various 
number are produced by all the common sources of 
sound, and may be easily demonstrated with an in- 
strument of the "sonometer'' type; a long gut or 
piano wire stretched on a sounding-board or box. 
Strike the string with a piano hammer (a small rod 
wrapped with cloth will do) at a point one-quarter 
the distance from one end to the other, and then 
touch it lightly in the middle with a feather or small 
wad of cotton; the fundamental note of the string 
will stop, but a note an octave higher will continue 
sounding. This octave tone is called the first over- 
tone, or the second partial (the fundamental being 
the first partial). Strike the string at one-sixth and 
touch at one-third, and you will hear the third 
partial. Strike at one-eighth and touch at one- 
quarter, and you hear the fourth partial. If you 
touch where you have struck, the partial correspond- 
ing to the point of touching will not be produced, or 
will be very faint; this shows that it is the striking 
and not the subsequent touching that produces the 
partial; which means that the upper partial is pro- 



PROTENSITY AND EXTENSITY 127 

duced along with the fundamental. With a Httle 
practice you can in fact soon acquire the abihty to 
pick out the partials without touching or stopping 
the string. 

In instruments of the horn or trumpet type, with 
proper blowing and without manipulation of the 
valves or slides, the partials up to the eighth or 
ninth may be made to sound without the partials 
below the particular one sounded in each case. 
This gives a sort of scale whose notes are far apart 
at the bottom and closer at the top, and in this scale 
we can play the melodies known as "bugle calls.'' 
Since these notes (with a modification of the sev- 
enth) are included in the diatonic scale (in the brass 
instruments of the modem orchestra we simply add 
the intermediate notes by manipulation of the valves 
or slides) we may reasonably suspect that such 
wind instruments have been important in fixing the 
notes of the modern scale. 

In another way the partials have helped to fix 
the intervals of the scale, especially the octave, the 
interval between the fundamental and the second 
partial, which is relatively strong in the human 
voice. In a room or cave some of the notes pre- 
viously sung are still vibrating while another is 
being sung (or played) so that the present note must 



128 A SYSTEM OF PSYCHOLOGY 

"harmonize" with the overtones of the previous 
note. 

The musical interval between two notes is meas- 
ured by the ratios of the vibration-frequencies of the 
two notes to each other; thus, the note of 256 vibra- 
tions per second and the note of 320 vibrations per 
second are separated by the same interval as the 
notes of 320 and 400, the interval, namely, of 4:5. 
The intervals separating the successive notes of 
the diatonic scale (c, d, e, f, g, a, b, c; or ut, re, 
mi, fa, sol, la, si, ut), may all be expressed by small 
fractions, and are f , ^, \f, f , ^, f , f|. The rela- 
tive rates of vibration of the notes separated by 
these intervals may, therefore, be represented by the 
numbers 8, 9, 10, lOf , 12, 13J, 15, 16. The rates 
of vibration of the harmonic partials (the partials 
of the voice and of musical instruments are prac- 
tically harmonic) are 1, 2, 3, 4, 5, 6, 7, 8, and so on; 
the second vibrating twice as fast as the first, the 
third three times, the fourth four times, and so on.^ 
It is evident that the diatonic scale is the series of 
harmonic partials from the eighth to the sixteenth, 

^ The harmonic partials are those whose vibration-rates are 
integral multiples of the rate of the fundamental. A partial 
whose rate is 2<j times that of the fundamental would be 
classed as non-harmonic. Tuning-forks, bells, and metal 
plates produce non-harmonic partials. 



PROTENSITY AND EXTENSITY 129 

with lOf substituted for 11, and 13J for 13 
and 14. 

The partials up to the ninth are, as said before, 
easily produced on wind instruments (and of course 
on stringed instruments, in isolation, by stopping the 
strings as described), so we are not surprised to find 
that in the earliest scales discoverable, in India, 
China, and the British Isles, these intervals are in- 
cluded. The notes employed in these scales are, 
as represented in our scale, c, d, e, g, and a|:[ , or 8, 
9, 10, 12, 13J. Now the most obvious thing about 
tl^e overtone series is the octave relation, 1 : 2, 2 : 4, 
4 : 8, etc., so that the intervals 8 : 10 : 12 : 14 : 16 
are equivalent to the intervals 4:5:6:7:8; and 
hence all the intervals of the primitive scale are 
really given by the overtone series up to nine, ex- 
cept that the seventh partial is replaced by a slightly 
lower note. 

The modification of the seventh partial is the 
first step in the process of simplification which has 
given us the modern scale; for as the series 8:9: 
10 : 12 : 14 : 16 gives no two intervals alike, the 
slight flatting of 14 to 13| replacing 12 : 14 = 6 : 7 
by 12 : 13^ = 8 : 9, or, still better, flatting to 13 J 
and so replacing 12 : 14 : 16 by 12 : 13J : 16 = 
9 : 10 : 12, thus duplicating intervals already in the 



130 A SYSTEM OF PSYCHOLOGY 

scale, simplifies matters much. In the same way, 
when it was desired to insert additional notes in the 
larger gaps, the notes chosen were not 11 and 13, 
but such notes as would introduce the fewest new 
intervals; and these would be the notes 8 : 9 above 
13J and 8 : 9 below 12, i. e., lOf and 15, which in- 
troduce only one new interval, 10 : 10§ = 15 : 16/ 
The scale as derived contains, therefore, only three 
different successive intervals; 8:9, 9 : 10, and 
15 : 16; the major tone, minor tone, and semitone. 
Having derived these three intervals, the ingenuity 
of musicians led to the combination of the inter- 
vals in other orders to fill out the octave, but the 
one which came nearest to the overtone series is the 
one which has survived in use. 

A still further development has displaced the 
diatonic scale, which is practically not used at all 
now. If a note is inserted between 8 and 9, 15 : 16 
below 9; and another 15 : 16 above 8, the two 
notes (8 xV ^nd 8 xe) are separated by an interval of 
2025 : 2048. The pairs of notes similarly placed 
between 10| and 12, and 13|^ and 15 are separated 
by the same interval, and the pairs between 9 and 

^ The interpolations of course made by sound, not by the 
abstract ratio; but the proper sound is obtained only if the 
physical conditions which are expressed by the mathematical 
ratio are observed. 



PROTENSITY AND EXTENSITY 131 

10, and 12 and 13J by a slightly larger interval. In 
the scale derived in this way — the chromatic scale — 
ab is slightly lower than g^, and so on. So much 
for the amplification of the scale; now for the sim- 
plification. The chromatic scale is absolutely im- 
practicable except for a few gifted musicians. If 
a single note standing between the proximate sharp 
and flat were substituted for the two, the resulting 
scale of twelve notes would be simpler, but too irreg- 
ular. The obvious way to reduce the irregularities 
is to divide the octave into twelve equal parts, doing 
away at one stroke with the distinction between 
ail and bb, etc., and with the two sorts of whole 
tones (8 : 9 and 9 : 10) and the two sorts of major 
fifths. Thus we have a scale called the equally 
tempered scale, which is a little less satisfactory than 
the chromatic scale in some respects, but immensely 
superior in other ways. The equally tempered 
scale has proved so superior to all other tempered 
scales (other scales constructed to simplify the 
chromatic scale) that it is universally adopted, and 
all modern keyed instruments are tuned in it — or, 
we might say,' tuned to it, since tuners do not always 
succeed. 

The Chinese and the Hindus achieved a twelve- 
fold division of the octave, as did probably the 



132 A SYSTEM OF PSYCHOLOGY 

Greeks also. Any people influenced by the har- 
monic partials and alive to practical musical needs 
was certain to hit upon some sort of tempered scale. 
The Chinese and Hindus went still farther, and 
worked out subdivisions smaller than the twelfth of 
the octave, but seem to have made little practical 
use of these minutely built scales. Savage peoples, 
who had not harmonic instruments (horns, etc.) and 
whose music was produced out-of-doors, seem to 
have developed scales not built in the octave at all. 
This statement applies to some North African 
tribes, at least, and to ancient Egyptians of low 
caste. Information on these matters is for the most 
part seriously defective, even in regard to existent 
tribes, and much observation has been rendered 
worthless by the assumption of the observer that 
the savages are attempting to use intervals repre- 
sented in the diatonic scale, and that their devia- 
tions from these ideal intervals are due to their 
clumsy vocalization and inaccurate "ear.'^ 

4. Timbre 

The character of the tones of different instru- 
ments, or, as we say, their timbre, is altogether de- 
pendent on the presence of overtones or upper par- 
tials. The particular partials present, and their 



PROTENSITY AND EXTENSITY 



133 



relative intensities, determine the voice of the in- 
strument. 

The partials depend on the fact that the string, 
or column of air, or other vibrating body, is vibrat- 



FiG. 9. 



Fig. 10. 




Fig. 11. 

Figures 9, 10, and 11 are intended to represent schematically the 
relations of fundamental and overtones in notes of the organ-pipe, 
violin, and clarinet, respectively. The pitch is represented by the 
length from left to right, and the intensity by the height from top 
tol)Ottom. The relative intensities of the partials in a given figure 
are somewhere near those actually existing in the characteristic notes 
of the instrument. In the representation of pitch the length of the 
partials is arbitrarily made inversely proportional to the vibration rate. 
Notice that in the case of the clarinet (fig. 11) the second partial is 
missing, while the third partial is relatively strong. 

ing not only as a whole, but in segments. The in- 
tensities of these segmental vibrations depend on 
the form and material of the sonorous body and the 
way it is excited or set in motion. The voice of a 
violin, for example, depends in large measure on 
the condition of the wood, glue, and varnish of 



134 A SYSTEM OF PSYCHOLOGY 

which it is made, and the way in which it is bowed. 
Pick the strings, and the note is not only short in 
duration, but has a characteristic timbre because 
the relative strengths of the partials are not the 
same as when the string is bowed. The difference 
between the tones of a cylindrical flute and a clari- 
net is partly due to the "bell'' on the end of the 
clarinet, but more to the excitation of the flute by 
blowing across a hole and of the clarinet by blow- 
ing through a reed. The note of the trumpet dif- 
fers from that of the cornet because of the differ- 
ent taper of its bore. 

5. Extensity and Intensity 

Extensities are comparable in the way in which 
we compare intensities, and we find difficulty in 
abstracting the extensity-differences from the more 
complex space-differences just as we find in the 
case of duration and time. The physical measures 
of just perceptible differences are found to increase 
with the extensities compared, but apparently 
not in such a simple way as is formulated for in- 
tensities in Weber's Law. In pitch, in general, 
when we can succeed in neglecting the metrical 
factor of scale relationships, differences seem equal 
when the corresponding differences in vibration 



PROTENSITY AND EXTENSITY 135 

rate are equal. This may mean equal diflferences 
in number of nerve endings stimulated. 

Intensity is influenced by extensity, and vice 
versa. It is well known that a small spot of light 
falling upon the retina is sensationally not so bright 
as a larger spot of the same physical intensity per 
unit of area. A weight of one gram resting on one 
square centimeter of skin feels not so heavy as a 
weight of ten grams resting on ten square centi- 
meters. A gustable solution applied to half of the 
tongue is productive of a stronger flavor than the 
same solution applied to a smaller area. These 
effects are in part due to the relatively greater ex- 
tent of margin of a small area, and the consequent 
greater reduction of stimulus energy through irradi- 
ation to surrounding areas, but there may be other 
causes at work. In the case of auditory sensation, 
the conditions are such as to appear at first the 
reverse of those described above; a high note of 
given energy sounding more intense than a low note 
of same energy. This is doubtless because a high 
note affects a fewer number of nerve endings, and 
hence the actual stimulating energy is greater per 
unit of nerve ending than in the case of the lower 
note. 

Intensity frequently affects extensity through the 



136 A SYSTEM OF PSYCHOLOGY 

spreading or irradiation just mentioned. The ex- 
citation from a strong stimulus spreads out over a 
larger area in the sense-organ than in the case of a 
weak excitation. This is readily demonstrated in 
vision by noting the apparent increase in size of an 
electric light filament as it begins to glow. 

The reader should note that our statement that 
intensity influences extensity, and vice versa, is meta- 
phorical, and that the exact statement in terms of 
the two characters and the corresponding features 
of the stimulus is that the stimulation-conditions 
which determine the extensity and the intensity of 
sensation are in certain cases, at least, mutually de- 
pendent. 



CHAPTER VIII 

LOCAL SIGNIFICANCE 
I. Localization and Local Sign 

Sensations of touch and temperature on any 
part of the body are "localized'^ more or less cor- 
rectly; that is, are felt as coming from the locality 
of actual origin. This discrimination must be 
based on diflferences in the sensations from the 
different regions, which sensations we have come to 
be able to refer to the proper places. Suppose, for 
instance, your eyes are closed, and some one noise- 
lessly touches you on the hand, using a small rod 
of cork to obviate temperature sensations. You 
can decide at once that it was on the right hand and 
not on the left; which is sufficient proof that the 
sensation from the one hand is different from the 
sensation from the corresponding point of the other 
hand. The important question is: What are the 
differences which serve as the basis of this local 
discrimination ? Differences in intensity, exten- 
^ sity, and duration can be ruled out, for variations in 

these regards do not influence localization except 

137 



138 A SYSTEM OF PSYCHOLOGY 

in extreme cases. Differences in quality are also 
excluded, for the tactual sensation has probably 
the same quality everywhere on the skin, and tem- 
perature sensations, which may certainly be ob- 
tained in different regions with identical quality, 
are also localized. 

The fact that localization does not depend on 
quality is more apparent in the case of the eye. 
Stimulations of different points of the retina (if not 
too close together) are always discriminated as dif- 
ferent, and by habitual association referred to the 
relative angular positions from which the stimulat- 
ing rays of light must come. The discrimination 
of positions in the visual field depends, in short, on 
the discrimination of positions on the retina. And 
though the hue of a color roused by a given light 
stimulus varies according to the part of the retina 
stimulated, there are many different points in the 
retina giving the same qualitative mixture, which 
are, nevertheless, discriminated. The hues, more- 
over, may be varied through the whole range of the 
spectrum without affecting the locality discrimina- 
tion; the discrimination, therefore, cannot depend 
on quality. 

The character of sensation which furnishes the » 
real basis for localization is thus demonstrable only 



LOCAL SIGNIFICANCE 139 

by a process of exclusion. The uniform associa- 
tion of this character with the space position of the 
end-organ prevents our separating it analytically 
from this spatial factor, but since the character 
must exist as a basis for the space localization, we 
give it the name of local significance, or particular- 
izing, local sign. Physiologically, local sign proba- 
bly depends on the individual end-organs which are 
active, but nothing more can be said at present/ 

2. The Discrimination of Local-Sign Differences 

In order that a difference in local signs may be 
noticed, it must have a certain minimal value, 
which, however, is variable. Similar points on the 
corresponding fingers of the two hands can nor- 
mally be distinguished, but if the hands are kept 
behind a screen for some time, and the fingers not 
stimulated, the patient tends to become uncertain 
as to which hand is touched. The signs apparently 

^ There is a theory that local signs are muscular sensation 
accompanying the primary sensation, or are the images of 
muscular sensation arising from the past experience of the 
muscular action necessary to bring the hand, or other mem- 
ber, to the spot on the skin with which the sign is connected. 
This theory is rather a work of supererogation, because it 
must assume a local sign of the sensation in order that it may 
rouse the proper muscular images; in other words, the theory 
does not touch the problem of local significance at all. That 
muscular sensation has a great deal to do in the discrimination 
and systematization of local signs is another matter. 



140 A SYSTEM OF PSYCHOLOGY 

are so nearly alike that the person forgets which is 
which unless he has a chance to freshen his memory 
from time to time. In general, the closer two points 
are on the skin, the nearer alike are the local signs 
of the sensations aroused therefrom; consequently, 
on any part of the body there is a certain minimal 
distance by which two simultaneously applied com- 
pass points must be separated, if they are to be felt 
as two. If the distance between the two compass 
points is less than the minimum, the two points are 
felt as one, because the difference in local signs is 
not enough for discrimination, although the two 
may be felt as " bigger ^^ than either alone, probably 
because more nerve endings are stimulated in the 
former case. 

The minimal distance of separation of two stim- 
ulating points felt as two is commonly known as 
the " two-point threshold, and the determination of 
this threshold is called ^* sesthesiometry." ^ 

^ Several explanations have been proposed for the physio- 
logical side of the two-point threshold, but so far it remains 
principally a matter for theory. A probable theory is based 
on the fact that all dermal nerve endings are connected with 
deeper-lying nervous structures, and that the endings con- 
nected with one deeper organ are interspersed in the skin 
with endings connected with other of the deeper structures. 
Any touch stimulus, therefore, is apt to affect two or more of 
the deeper organs, and if we assume that the local sign is 
associated with the deeper structure rather than with the 
dermal ending, it follows that a touch gives a combination of 



LOCAL SIGNIFICANCE 141 

In order that practice may influence the local- 
ization of sensation, and in order that differences in 
local sign may be discriminated at all, it is neces- 
sary that the signs to be discriminated shall at some 
time occur in independence of each other. If two 
signs or groups of signs are habitually aroused to- 
gether, it is difficult to discriminate them; if they 
are invariably aroused together, discrimination is 
impossible. Touches on the opposite edges of two 
adjacent fingers are easily discriminated; touches 
on the apposed edges are not discriminated so read- 
ily, especially if near the palm; and if two nor- 
mally apposed spots are simultaneously stimulated, 
the experience is apparently of a single touch. This 
last phenomenon results from the fact that the 
apposed areas are usually stimulated by a single 
object. 

In the case of the eyes, the necessity of indepen- 

sensations of different local signs. The relative intensity 
of the sensations in a given sensation-combination is accord- 
ingly the datum for the minute localization of the mass. This 
theory is supported by the fact that practice greatly reduces 
the two-point threshold, and by the fact that in many cases 
a single touch is perceived as two or even three. 

The threshold varies from one millimeter or less on the tip 
of the tongue and the finger-tips, to several centimeters on 
the middle of the back. It bears no definite relation to the 
intensity-threshold, or to the intensity difference threshold 
on the different parts of the body. It is smaller on the more 
motile portions of the body. 



142 A SYSTEM OF PSYCHOLOGY 

dent stimulation is strikingly made evident. Nor- 
mally, when any point in one eye is stimulated, a 
definite corresponding point in the other eye is stimu- 
lated in practically the same way. Hence, if under 
experimental conditions one eye alone is stimulated 
by light, the person is unable to tell, from that 
stimulation alone, which eye is affected.^ This 
peculiarity of vision is of practical importance, for 
the stimulation of corresponding points in the two 
eyes produces single vision; that is to say, if two im- 
ages nearly identical in form and detail, are thrown 
on corresponding portions of the retinae, a single ob- 
ject is seen, whether the two images come from a 
single "real" object or from a stereoscopic picture. 
On the other hand, if the images of an object fall on 
portions of the retinae not corresponding, the object 
is "seen double.'' This effect is easily produced 
by crossing or "walling" the eyes, or by pushing 
on the ball of one eye with the tip of the finger (on 



^ This may be demonstrated in a dark room. Let the per- 
son gaze at a feeble light, as a pinhole gas flame, or phos- 
phorescent spot, having both eyes open and his head fixed in 
position. You may bring a card in front of one of his eyes, 
and he will be unable to tell which eye is seeing. The light, 
if a gas flame is used, must be so dim that he cannot see the 
card itself, and he must refrain from winking. Another 
demonstration may be made with a pair of spectacles, one 
lens plain and the other slightly prismatic. The person will 
not know which image is displaced. 



LOCAL SIGNIFICANCE 143 

the lid, of course), or by bringing a prism before 
one eye. 

Corresponding points, as the term is used in 
psychology, may be defined as points on the two 
retinae which are normally stimulated by rays of 
light from a single point in an object upon which 
the eyes converge. Corresponding areas of the 
retinse are, accordingly, areas which correspond 
point for point. 

3. Local Sign In Auditory Sensation 

It is possible that local sign plays an important 
part in auditory sensation. According to the Helm- 
holtz theory, pitch really reduces to local sign. If 
each rate of audible vibration should stimulate a 
small group of hair cells on the basilar membrane, 
each corresponding sensation would have a specific 
local sign, and these, differing from one another in 
accordance with the separation of the hair cells 
in the series, would form a linear series. The sen- 
sations would not be localized, there being no mus- 
cular mechanisms to assist in the associative proc- 
ess; so the series of pitches would remain a series 
of practically pure local signs. 

Assuming that the Helmholtz theory is not cor- 
rect, and that pitch is primarily extensity of audi- 



144 A SYSTEM OF PSYCHOLOGY 

tory sensation, local signs may still be important 
in connection with tones. Each pitch may come 
to be associated with a certain local sign, namely, 
that of the group of end-organs at which the excita- 
tion on the basilar membrane ends. Thus, the 
series of local signs becomes the series of symbols 
of the extensities primarily constituting pitches. 
Extensity itself can be estimated only approxi- 
mately by direct observation; this is true in both 
visual and tactual estimation, and it is possible that 
the person of "uneducated ear" distinguishes pitch- 
differences crudely because he attempts to judge in 
this way. The person of "musical ear," on the 
other hand, has possibly acquired the ability to 
notice the local signs, which lend themselves to 
more accurate identification, and has formed an 
accurate system of associations between these local 
signs and the marks of musical notation. Nothing 
is more certain than that musical and non-musical 
people employ different methods of estimation of 
pitch, and that the cultivation of the "ear" is a 
process of learning how to observe. 

The immediately foregoing remarks do not apply 
to cases of organic defect in the auditory appa- 
ratus. There are persons who can never learn to 
distinguish pitches accurately; some peculiarity of 



LOCAL SIGNIFICANCE 145 

their aural mechanism doubtless prevents the ex- 
citations from being sharply defined, a condition 
which may properly be designated amblacousia. 

4. Olfactory Local Sign 

Local sign may have something to do with the 
baffling composition of odors. Some of the peculiar 
similarities, and differences of smell sensation may 
really be identities and differences of local sign. 
We must remember that we never experience the 
local sign of dermal or visual sensation without its 
associative connection with space, nor local sign 
of auditory sensation apart from the corresponding 
extensity; hence, local sign unassociated with either 
of these factors, or associated with extensity in a 
non-serial way, would not be naively identified. 



CHAPTER IX 

RELATIONAL ELEMENTS IN THE CONTENT OF 
CONSCIOUSNESS 

I. General 

In discussing sensations we have necessarily dis- 
cussed the relations in which they are experienced, 
but with reference always to the sensations. Now 
we must focus our attention on the relations them- 
selves, and consider them in their turn as elements 
of content. 

Just as you directly perceive sensations, so you 
perceive relations. This red is perceived as differ- 
ent from green; as like that other red; as brighter 
than this one; as lying on the table; as more beau- 
tiful than this dingy color; and so on. But it is 
not only sensations that are involved in complexes 
of relations; emotional content (assuming for the 
present that it is a specific content) is equally in- 
volved with the relational factors. 

In the treatment of relation we encounter much 

more diflficulty than in the treatment of sensation, 

146 



RELATIONAL ELEMENTS 147 

because of the way in which relations complicate 
themselves in groups which seem like single rela- 
tions; and also because of the elaborate processes 
through which we learn to perceive certain of these 
systems. We can develop in this chapter only the 
general line of analysis to which this content must 
be submitted, and amplify only enough for the pur- 
poses of the other portions of our work which come 
into close connection herewith. 

The most conspicuous peculiarity of relation- 
content is that it has no definitely assignable ner- 
vous process corresponding to it. We know of no 
" centre ^^ in the brain for the perception of relations, 
and we do not know that it is a cortical function at 
all. We must not suppose that perceived relations 
depend on, or are functions of "brain-paths," or 
"association fibres;" brain-paths represent simply 
connections established between different factors 
of content, by the operation of which the factors 
function together; the physiological connection is 
not the same thing as the experienced connection 
or relation, and the physiological connection may 
function perfectly whether a specific relation is 
experienced or not. It is true that there are a 
number of motor processes which assist in the per- 
ception of relation, but their neural consequences 



148 A SYSTEM OF PSYCHOLOGY 

are no more to be considered as the counterparts 
of the experienced relations than the neural excita- 
tion caused by the movements of the eye are to be 
considered as the counterpart of the color sensa- 
tion, in the obtaining of which the eye-movements 
assist. These points will become clearer as we 
proceed to the analysis of complex perceptions. 
For the present we may repeat, that while we in- 
cline to believe that there are specific brain proc- 
esses corresponding to the relational content of 
consciousness, as there are to sensational content, 
the belief is as yet merely a detail of the general 
a priori theory of the relation of nervous process 
to experience. 

The enumeration of elementary relations or 
groups of elementary relations is a diflBcult, not to 
say impossible, procedure in the present stage of 
psychological analysis. The greater number of 
familiar relations are doubtless complex. The rela- 
tions of causality, of inadequacy, of up and down, 
and so on, are really involutions of a number of 
relations whose final analysis is, perhaps, not yet 
to be made. To particularize: the relation which 
we call causality involves the relation of succession 
— or, perhaps, simultaneity — the relation of in- 
variability, and, according to one view, the complex 



RELATIONAL ELEMENTS 149 

of relations involved in the " transfer of energy/' ^ 
Take now the factor of succession; is it a simple 
relation? Probably not. It involves the relations 
of betweenness and difference, with a certain re- 
semblance, and the peculiar relation to other phe- 
nomena involved in time. 

As examples of relations which are 'probably 
elementary we may name the following: difference, 
identity, similarity, greater, less, betweenness, direc- 
tion (peculiar to space), a relation peculiar to time, 
agreement, and possibly the relations of good and 
bad. At any rate, it is diflficult to see how these can 
be resolved into any other relations: but the list 
is only a suggestion. 

2. Platonic Ideas and Matter 

The importance of relations in the content of 
consciousness, and in the supposed world lying 
behind experience, has always been recognized, and 
perhaps rather overestimated than underestimated. 
The '* Ideas'' of the Platonic philosophy are nothing 
less than systems of relations; at least this phi- 
losophy is pretty good common-sense when the 

* Of course, these relations are not perceived in this combina- 
tion; that is to say, we never perceive causation outright, but 
perceive a part and imagine the rest. 



150 A SYSTEM OF PSYCHOLOGY 

"Ideas" are so interpreted. The philosophy 
called "Idealism" always emphasizes the relations 
in the content, making them the prime or essential 
part, and the sensory factor trivial or secondary. 
Surprising as it may seem, the apparently opposed 
theory of "Materialism" has simply abstracted 
some of the most universal and characteristic re- 
lations from the content of consciousness and given 
them the names of " Matter'' or " Substance." So, 
from the psychological point of view, these two 
systems are more nearly identical than opposite. 
Empiricism, which we believe to be a more adequate 
view, recognizes the importance of relational and 
non-relational content, and does not attempt to set 
either above the other. 

3. Intellect 

The perception of relation is commonly called 
intellect, in both scientific and popular discourse. 
In common language we speak of a man as being 
"intellectual" in so far as he is quick, accurate, or 
thorough in the noticing of relations; without re- 
gard to his keenness of sense perception, or his emo- 
tional capacity, or his will. Of course these fac- 
tors of his total experience are never sundered, and 
each is important for the others, but high develop- 



RELATIONAL ELEMENTS 151 

ment of one does not imply development of the 
others to the same degree. 

4. The Reality of Relational Content 

There are several theories of relation-content 
which attempt to explain it away. The so-called 
"sensationalist'^ theory supposes the relation to be 
a sort of fusion or combination of the sensations. 
The "motor" theory supposes that our reactions 
to the sensory content constitute both the relations 
of the content within itself and to other content. 
While we do not wish to underestimate the im- 
portance of these theories, we wish to point out that, 
psychologically, they are only statements of the 
conditions and consequences of the experience of 
relations, and not explanations of the experienced 
relations themselves. The fact remains that re- 
lations are really perceived, and the attempt to 
evade this by substituting for the relation a fusion 
of sensations or a motor process is a waste of energy. 
The relation is as much a reality as the factors it 
relates, and we perceive it just as truly as we per- 
ceive them. 

We cannot deal adequately with relation in ab- 
straction from the other forms of content without 
getting outside of the field of psycholog}\ Two 



152 A SYSTEM OF PSYCHOLOGY 

sciences — or two branches of the same science, if 
you choose — deal specifically with relations: these 
two are logic and mathematics, and the serious 
student of psychology is advised to make himself 
well acquainted with both of them, not for their 
specific methods or results, but for their points of 
view. 



CHAPTER X 

IMAGES AS ELEMENTS OF CONTENT 
I. Imagination and " Image-Types " 

We have already referred to the prevalent doc- 
trine of images as copies of sensations, or copies of 
sensation-complexes. This doctrine is older than 
Aristotle, who stated it pretty clearly, and who, 
perhaps, gave it its definite formulation; and it 
has been incorporated in some form in practically 
every general theory of psychology since his time. 
In modern times impetus has been given to the the- 
ory by the introspective and experimental work of 
Fechner and Galton, in whose steps many psy- 
chologists have followed. 

Galton alleged that there are — or may be — 

images of different senses, but that images of 

vision and audition are the most important in the 

consciousness of adults. Galton compiled a "ques- 

tionary'' which was sent to, and answered by, a 

great many persons of all sorts; the object of 

the questionary being to determine the kinds and 

153 



154 A SYSTEM OF PSYCHOLOGY 

relative clearness of the images possessed by these 
persons/ 

Imagination as an actual process or function 
cannot be denied, nor is there any doubt that when 
you imagine certain objects they will have a visual, 
or auditory, or other sensory reference. Some psy- 
chologists have denied the existence of images of 
taste and smell; indicating thereby a personal 
peculiarity, for the olfactory and gustatory features 
of imagination are for some persons the most vivid. 

Muscular imagination has received due credit 
in the various attempts at analysis, and it has been 
stated with apparent justification that much of our 
"thinking," or trains of representation, goes on 
through the activity of the "images" of spoken 
words, and that these "images" are usually mus- 
cular, {. e., representations or reproductions of the 
muscular sensations which occur in speaking the 
words. In reality, the alleged muscular images 
may be muscular sensations. (See below.) 

In accordance with the accepted view, individu- 
als are classified under "types" corresponding to 
the sorts of "images" they employ most constantly 

^ The intention of the questionary and Galton's views on the 
subject of images are best obtained from his Inquiries into 
Human Faculty. The gist may be found in James, Principles 
of Psychology, II, 51-57. 



IMAGES AS ELEMENTS OF CONTENT 155 

and readily. The predominance of images of the 
muscular sensations marks one as of the "motor 
type/' and the predominance of images of the audi- 
tory or visual sensory sorts marks one as of the 
" auditory type/' or the " visual type/' A person of 
either motor or non-motor type may be of the "verbal 
type/' i. e., may employ "images" of heard or seen 
or spoken words. The terminological development 
has been carried still farther, but we need not pur- 
sue it beyond this point.^ 

When we come to the actual determination of 
"types" in accordance with the Aristotelian theory 
of "images/' the trouble begins. Determination 
by the simple introspection upon which the ques- 
tionaries depend is usually unsatisfactory to the 
patient, and still more so to the persons conducting 
the investigation. Several auxiliary tests have been 
devised, but they all depend on the interpretation 
of the results by assumptions which beg the whole 
question. 

As regards the physiological processes causing 
or corresponding to imagination, the most natural 
theory based on the Aristotelian view is that the 

^ A person of the auditory type is sometimes called an 
^^audile"; of the visual type a 'Wisile." '^Tactile," "olfactile'' 
and ^'gustile" have been used also, but are not in such high 
repute. ** Motile" is in good usage. 



156 A SYSTEM OF PSYCHOLOGY 

imagination process (production of the "image/') 
is simply a revival of the sensation process in a 
weaker form. The imagination-centres are, ac- 
cordingly, supposed to be identical with the sensory 
centres, and the determinative difference between 
the imagination process and the sensation process 
is considered to be due to the initiation of the latter 
from the sense-organ, and of the former from some 
other brain-centre; the currents from the periph- 
eral organs being supposed to be more powerful 
than the intra-cerebral discharges. This theory 
of the brain process on which imagination depends 
.was quite widely held a decade or two ago, but it 
is now believed that the imagination process de- 
pends on a portion of the cerebrum contiguous to, 
or bordering on, the sensory area of the cortex. 

We ought not to consider an "image" as a spe- 
cific content, or a specific form of content, until we 
have more proof of the existence of that sort of an 
"image.'' Revived or false sensations probably 
do occur (the "subjective" sensations of the physi- 
ologist) but they are not what is meant by "image" 
or imagination. Actual normal sensations from the 
various organs may assist us in representation or 
thinking, but they are not a new form of content 
on that account. Imagination is a fact of con- 



IMAGES AS ELEMENTS OF CONTENT 157 

sciousness; it is a way of being conscious of content 
of various sorts, and not a specific content, so far 
as we are able to determine/ 

The specific sensory reference in imagination, 
which is the basis of the Aristotelian theory, is 
imparted in several ways, two at least of which we 
may point out. The sensory tang may be given 
because the object of which we are thinking was an 
object for the sense in question when experienced 
directly. The visible features of an object may be 
the important characteristics for one man, and to 
these principally he attends. Another man may 
attend principally to the sound made by the ob- 
ject. In recalling, or thinking, of the object, the 
first man will recall it as a visible object, and the 
second as an auditory object; each will think of it 
as it impressed him. But it is an unsafe leap from 
this bald and unexplained fact to the assumption 
that the first man has a " copy" of the visual sensa- 
tions and the second a '^copy^' of the auditory sen- 
sations. 

In some cases the mechanism by which the sen- 
sory mark is given is assignable. When sensations 



^ It is convenient to use the term "image'' to designate the 
represented content, and we shall do so, in spite of our dis- 
sent from the general belief as to its nature. 



158 A SYSTEM OF PSYCHOLOGY 

from a definite sense, or sensations which are the 
normal concomitant of that sense, occur along with 
imagination, they tend to give the imagination the 
corresponding tang. This may be the means by 
which the influence of the preceding direction of 
attention to the object is realized, or it may be in 
some cases the agency which counteracts such in- 
fluence. The sensations in question may be from 
the sense to which the imagination is ascribed; 
faint sensations from the retina, i. e., of light, may 
give the visual reference to the " image ^^; but 
usually the sensations are from the motor apparatus 
functionally connected with the sense-organ. 

In thinking of a visual object, e, g,, of an illumi- 
nated sign, there are movements of accommodation 
and convergence of the eyes, if the person is of the 
"visual'' type. In thinking of the sound of an 
orchestra there are changes in tension of the mus- 
cles in the tympanum of the ear, or in the neck- 
muscles. If you fix your eyes on a point on the wall 
you will probably find it difficult to call up the pict- 
ure of a ship under sail; let the eyes wander freely 
and the picture comes up readily. Fixate steadily 
a square of mosquito netting, and the picture will 
probably not come at all; this is because the net- 
ting offers an excellent object for steady fixation. 



IMAGES AS ELEMENTS OF CONTENT 159 

Some persons find a great decrease in facility of 
visual imagination when the eyes are under the in- 
fluence of atropine; in the case of these persons the 
sensations of accommodation are important in mark- 
ing the image. 

If you can readily recall or imagine odors try the 
following experiment: take a deep breath, and have 
some one else name an odor just as you begin to 
exhale slowly through the nose; you will find that 
you do not get the image until you begin to inhale, 
and probably not then if the inhalation is slow. 
Sniff, and the image appears at once. Certain 
persons, whose taste images are extremely vivid, 
cannot get them unless the tongue is allowed to 
move. 

A type of experiment which is noteworthy may 
be exemplified in the following way: put the vocal 
organs in position to say " Ah,'^ and, holding them 
so, try to think or image the word " soap-bubble," 
or "parsimonious." The word will, in most cases, 
not "think" fluently. Such results have been held 
to demonstrate that the images of the words are 
"motor." It really shows only the close connec- 
tion between the muscular sensations from the vocal 
organs and the imagining of the words. 

The very ease with which individuals have been 



160 A SYSTEM OF PSYCHOLOGY 

convinced that what they before believed to be 
"visuar^ or " auditory ^^ images were really '^ mus- 
cular/^ as a result of experiments like the one just 
described, is in itself sufficient to raise a serious 
presumption against the Aristotelian theory. Like- 
wise, the maintenance by certain persons, among 
whom are trained psychologists, that they never 
have any images such as Galton and others describe, 
is a significant circumstance. If the sensory ref- 
erence is not intrinsic, but dependent on the me- 
chanical interpretation of attendant sensations, these 
anomalies are quite explicable. 

2. The Function of Imagination 

Although the discussion of imagination belongs 
logically to the later chapters of this book, we must 
anticipate somewhat, in order to describe the be- 
havior of the content when apprehended imagina- 
tively, and the way in which that behavior modifies 
the total content in perception. 

We are naively disposed to think of imagination 
as a play of fancy which may be amusing and in- 
teresting, but hardly as subserving the more prac- 
tical and prosaic processes of thought. As a mat- 
ter of fact, this latter is just what imagination does. 
Imagination is the basis of memory and of all rea- 



IMAGES AS ELEMENTS OF CONTENT 161 

soiling processes, and upon it depends the percep- 
tion of objects in the world about us. 

Whatever has been perceived may be imagined 
in much the same form. Having seen a lion and 
heard it roar, I may on some subsequent occasion 
imagine a lion of the same appearance, and with 
the same sort of a roar. The content is indeed 
never exactly the same in imagination as it was in 
perception, but the difference may be unimportant. 
This approximate repetition of a former content is 
the reproductive function of imagination, and we 
speak of it simply as reproductive imagination. 
According to the Aristotelian theory the content 
is an approximate copy of a former sense-con- 
tent. 

On the other hand, content may be imagined in 
forms and combinations quite different from those 
of the original perception, and hence we are able 
to imagine things which, strictly speaking, we have 
never perceived. Sensory content experienced in 
one perception may creep in with content of another, 
or certain sensory factors may be eliminated from a 
former content. New relations may be introduced, 
and old relations modified. In consequence of 
these changes we have not only a general modifica- 
tion by which the content of all experience tends to 



162 A SYSTEM OF PSYCHOLOGY 

lose its individuality, but also the special ease which 
we call creative imagination. 

One who imagines a perfectly "impossible'' 
animal, a griffin or a "goop'', is imagining a con- 
tent composed or built up of the elements of a mass 
of content which he has previously perceived. It 
is only necessary to modify the human figure by 
changing certain contours in ways which are al- 
ready familiar, and the "goop" is invented. Any 
one of us could imagine all the details separately, 
or in other combinations; otherwise we should not 
appreciate the "goop;'' the notable feat was in 
imagining them combined. In poetry, the content 
suggested is such as we can all imagine — if the 
poetry appeals to us — but the poet has combined 
it in new ways. The scientist, in discovering a 
new principle, is able to imagine what he has never 
perceived, by imagining old content in new combina- 
tions; then, if his imagining has been successful, 
he is able to use new methods or arrange new con- 
ditions of experiment, so that what he imagined be- 
comes now perceived, or he is able to demonstrate 
his results logically. 

In creative imagination the creator is aware of 
the modification of the content. Along with the 
rest of the content he has the peculiar factor which 



IMAGES AS ELEMENTS OF CONTENT 163 

we call newness, or novelty. He is aware that his 
content is a new combination. But in the general 
modification of content which we mentioned above, 
the person is less apt to be aware of the changes. 
The fisherman who magnifies into a three-pounder 
the minnow which escaped; the student who re- 
lates the hard-luck story of how he "failed'^ in an 
examination through no fault of his scholarship; 
are in many cases quite sincere, and base their tales 
on imagined content which has undergone progres- 
sive "improvement^^ since it was experienced in 
perception. 

A distinction has frequently been made in the past 
between the image and the idea. The image was 
supposed to be the special content in imagination, 
and the idea to be that to which the image referred, 
or which it meant; or else the idea was supposed 
to be both the image and its meaning taken to- 
gether. This view can be expressed by saying that 
the image present to consciousness means some- 
thing (some former content) which is not " present.'* 
The introduction of the content image does not 
seem to answer the question as to how consciousness 
is able to grasp what is not "present*' to it, and it 
seems that instead of trying to dodge the issue we 
might as well admit that we can be conscious of 



164 A SYSTEM OF PSYCHOLOGY 

content which is not presented: in which case the 
copy-image is a useless supposition. 

If we do not postulate a specific image-content, 
the distinction between image and idea is of no 
practical value unless we are willing to make it in 
the way in which it is made in every-day language. 
We do commonly discriminate in our use of the 
two terms, using "idea" in a general sense, and 
" image" to signify a form of idea in which the sense 
factors perceptible in a single physical object or lim- 
ited group of objects, are especially emphasized. 
Thus when I "think" of the pyramids of Egypt, I 
usually have a content which combines vague ele- 
ments of geometrical form with more definite frag- 
ments of representations of their probable builders 
(drawn of course either directly or indirectly from 
pictures and written descriptions), with a "feeling" 
of great distance from me, and with some actually 
presented muscular sensations which normally ac- 
company the lifting of a heavy weight. These are 
not the only factors, but they are typical of what 
the idea of the pyramids involves. It is possible 
to think of the pyramids in another way, in which 
the monuments themselves, as perceptible objects, 
become more prominent, and their relations to 
other things become less important. They are 



IMAGES AS ELEMENTS OF CONTENT 165 

then thought of as concrete objects in which color, 
form, and weight-content become predominant, and 
the factors of distance, antiquity, construction- 
problems, and personal and racial connections are 
minimized. It is useful to call the content of the 
former way of thinking an idea, and the content of 
the latter an imager but this is not to be taken 
as an accepted scientific usage, and the two terms 
must be used with caution. 

So far we have been speaking especially of the 
sensation-content in imagination; but relations are 
also imagined. A composite sensory content is 
presented in a complex of relations, and when we 
imagine a similar content it also is set in and per- 
meated by similar relations. We have shown above 
that in what we have called an image a limited 
group of sensory content may be important, as 
against the importance of a wider group in what we 
have called an idea, and we should also point out 
that in the idea the relations which enter into the 
content are to a large extent external to the central 
feature, while in the image the relations within the 
central factors of content are the most important, 
the external relations sinking into insignificance.^ 

* The increasing difficulty of arousing ^'images/* which fre- 
quently accompanies prolonged scientific training, is partly 



166 A SYSTEM OF PSYCHOLOGY 

In the instances given the central content is con- 
stituted by the features intrinsic to the pyramids 
themselves, as perceptible objects, and the ex- 
ternal relations are the relations to geography, 
engineering, the peculiarities of the builders, etc. 

It is possible to have an imaginative content in 
which the relations are the central feature, and the 
sensory factors are purely incidental. Such a con- 
tent is a further development of what we have above 
described as the idea, in the common parlance, and 
is properly called an abstract idea, or concept} 

The three types of content in imagination are 
therefore what we may call the image, the idea, and 
the concept: and we maintain that, as content, ab- 
stracted from the mode of being conscious of them, 
they involve only sensation and relation.^ 

The difference between the image of a horse and 

the idea of a horse ought to be already clear to the 

reader. In thinking of a horse of such a size and 

due to the habits of ideating engendered by that training. 
The scientist habitually apprehends all data in relation to 
other data, and loses to a greater or less extent the power to 
isolate which is characteristic of the artist. 

* The concept is sometimes identified with the Platonic Idea, 
and it may seem that we have committed ourselves to this 
view; but that is not quite the case. 

2 This statement is to be taken with the question previously 
raised; whether feeling is ever strictly imagined: but if feel- 
ing is a form of sensation, the statement is accurate without 
qualification. 



IMAGES AS ELEMENTS OF CONTENT 167 

color and attitude, and with that sort of qualifica- 
tion only, you "have an image"; but if you are 
simultaneously conscious of the usefulness of that 
animal as a beast of burden, or his importance as 
an enemy in an encounter, or his evolutional re- 
lation to other animals, or his need of hay and 
grain, you "have an idea/' Now just carry this 
differentiation a step further, and let the particular 
horse dwindle in significance, and the relations 
to burdens, oats, and so on, become more emphatic, 
and you "have the concept '^ of a horse. 

The preceding illustration makes apparent an 
important fact about concepts, and one which is 
sometimes overlooked. There are as many dif- 
ferent concepts of a horse as there are different in- 
dividuals who conceive it — in fact, each individual 
has many concepts of the equine species — differing 
according as they emphasize this or that set of 
relations; and yet in the large sense the concepts 
agree, since an animal which will agree with the 
concept of the zoologist or the artist will also satisfy 
the concept of the hostler. (The specimen which 
is ranked high under one concept may, however, 
be ranked low under the other.) 

While the various concepts of a horse held by 
different individuals pretty generally agree in func- 



168 A SYSTEM OF PSYCHOLOGY 

tion, there are other sorts of concepts which do not. 
The concept which one man has of morality, or of 
a moral being, is often incommensurable with the 
concept held by another man on nominally the same 
subject. This is probably because the concepts 
of neither are adequate; that is, neither has grasped 
a really definite and coherent system of relations. 



CHAPTER XI 

RETENTION, MEMORY, AND RECALL 
I. Retention 

As we have indicated already, one general con- 
dition of imagination is the previous perception of 
what is imagined, although the content in imagina- 
tion does not necessarily have the same form and 
combination which it had in the former perception 
or perceptions. One who has never perceived 
light — one blind from birth — cannot imagine color,^ 
and a similar limitation applies to any other sen- 
sation, because sensation cannot be built up from 
anything else. As with sensations, so with rela- 
tions; if they are not first apprehended, they can- 
not be conceived, although we may form concepts 
involving relations which have not previously been 
experienced in the exact combination in which they 
occur in the concept. A person who had never 
witnessed the transformation of a substance from 
solid to liquid, and vice versa, might conceive of 

* The blind man, by noting what others say about the ob- 
jects he perceives through touch, may be able to talk intelli- 
gently about their colors, and may not even know that he 
does not know what color is. 

169 



170 A SYSTEM OF PSYCHOLOGY 

liquefaction and solidification, but he could do so 
only if he had noticed the difference between the 
two states of substance, and had noticed modifica- 
tions of other sorts. 

The dependence of imagination on previous per- 
ception, although an undoubted fact, may not be 
so rigid as it is represented in such statements as 
those we have made above. Just as there are in- 
stinctive tendencies to actions which the individual 
has not learned to execute — tendencies due to the 
structure with which the individual is endowed by 
virtue of his place in the animal kingdom — so there 
may be instinctive tendencies to be conscious in 
particular ways, due to the nervous constitution of 
the individual and not to his experience. Until 
this possibility is excluded we can merely say that 
the dependence of imagination on the previous 
experience of the individual in the way described 
above is the general or usual fact. 

The dependence of imagination on perception is 
given the functional name of retention. In some 
way, the effects of the past experience or content 
have been preserved and so the present imagina- 
tion made possible. We do not know exactly 
what it is that is retained, but psychologists are 
accustomed to designate it plurally as traces. The 



RETENTION, MEMORY, AND RECALL 171 

experience leaves its traces, and through some 
activity initiated or facilitated by these traces 
the content is later revived as an image. Some 
theorizers claim that these traces are only phys- 
iological; modifications in the brain and its ap- 
pendages; others insist that there are mental traces 
also. 

On the whole, the doctrine of mental traces seems 
to be not an explanation of the dependence of im- 
agination on perception, but a symbolic statement 
thereof which adds nothing to our knowledge on 
the subject. 

The first notable feature of retention is the fact 
that it varies with the individual. One man, hav- 
ing experienced a certain content, retains it for a 
long time; another, under similar conditions, quick- 
ly loses the effects of what he experiences. This 
difference shows plainly in memory; we find the 
one man able to recall isolated bits of past experi- 
ence with ease and accuracy, while the other man 
requires all sorts of aids in order to recall his simi- 
lar experiences. The differences show also in the 
creative imagination; the wealth and facility of im- 
agery of some individuals as against the poverty and 
sluggishness of others is due in part to the extraor- 
dinary way in which all sorts of experiences stick 



172 A SYSTEM OF PSYCHOLOGY 

in the minds of some, and the difficulty with which 
they are retained by others. A great deal of individ- 
ual variation is due to the factors we are to take up 
next; but after allowance is made for them there 
seems to be a residue of personal diflFerences as yet 
unanalyzed. 

In the second place, experiences which are 
strongly impressed, that is, are strongly attended to, 
or are repeated several times, are more firmly fixed 
and retained than are experiences not having that 
advantage. This accounts for one sort of individual 
peculiarit}- two persons may observe the same 
phenomena, and afterwards each will be able to 
recall more fully the things to which he w^as specially 
attentive. A man fails to recall the color and style 
of the costume of the woman to whom he talks for 
half an hour, while his wife after one glance would 
be enabled to recall these details and a great many 
more; the man does not attend to sartorial feminine 
details, although he undeniably sees them. The 
effects of repetition are too familiar to need ex- 
emplification. 

In the third place, all effects of experience tend 
to disappear with the lapse of time. One might say 
that (to use an ancient analogy) the mind is like a 
tablet of wax or clay, upon which experience writes. 



RETENTION, MEMORY, AND RECALL 173 

The firmer the wax and the deeper the engraving, 
the more permanent the inscription; nevertheless, 
all inscriptions tend to become in time illegible 
through the slow process of disintegration of the 
surface of the tablet. Writing that is to last as long 
as the tablet must be scratched in deep at the first, 
or else the lines must be often retraced. 

In many cases, content whose traces are ap- 
parently obliterated is really retained. As we say 
in common terminology, things forgotten for years 
may return to memory with great vividness. The 
causes of this abeyance are obscure; in part it de- 
pends on associative factors, as will be made clear 
in the next chapter, but over and above the part 
played by association there is an unexplained factor 
in the variation in facility with which the traces of 
past experience, or content, become active. This 
slight obscurity is an important basis of the pseudo- 
scientific theories of " subconsciousness" with which 
we will have to deal later. We must remember that 
retention is only a name for the fact that a past 
content is subject to being re-experienced in imagi- 
nation, and that the only proof that a content is 
retained is in its being imagined; and, conversely, 
if any content of former experience is imagined, 
that is prima facie proof that it has been retained. 



174, A SYSTEM OF PSYCHOLOGY 

even if the period between the original experience, 
and the reproduction is fifty years. 

What has been once experienced may not return 
to consciousness in imagination, but may be effec- 
tive in another way. If you learn the lines of a 
poem to-day, you may have "forgotten" them by 
next month, and be able to repeat none of them. 
Yet, you will find that the relearning of the poem 
requires less time and energy than the first learning; 
this is largely a matter of association, but not al- 
together. 

The retention of the various impressions is facil- 
itated, and in fact the retention of complex content 
is made possible, by association. Under that head- 
ing, as well as under the headings of memory and 
recall, retention must be further discussed. 

2. Memory 

The term memory is used in psychology in prac- 
tically the same sense as in common parlance, but 
certain biologists are in the habit of using the term 
in another way; a practice which has brought about 
a great deal of confusion and unnecessary conflict 
of statement. If an animal acts upon any stimulus 
in a way which is the result of previous stimulations; 
if his conduct or experience (assuming that we know 



RETENTION, MEMORY, AND RECALL 175 

something about his experience) is based on the 
experience of the past, it is said by some writers 
that the memory of the past experiences or stimula- 
tions is demonstrated. There would be no objec- 
tion to this use of the term to designate the influ- 
ence of the past nervous processes on those of the 
present, if it had not been used so long to mean 
something more specific. 

Specifically, memory means the consciousness of 
any content, with the coincident consciousness that 
the content has been experienced before {i. ^., rec- 
ognition), and at some more or less definite date. 
If I remember a train wreck in which I was a par- 
ticipant, I am conscious of it now, (in the way of 
reproductive imagination), and also conscious that 
it happened awhile ago; I may be aware of the 
exact period at which it occurred, or I may not, but 
I at least locate it in a certain period of my past. 

It will perhaps occur to the reader that the 
greater part of my past experience, however much 
it may modify my present experience and activity, 
is not remembered. For example: my reading 
and writing are the result of a number of definite 
experiences of my early life, yet I do not remember 
the content of these experiences, nor can I remem- 
ber them if I try. If some one calls you by name. 



176 A SYSTEM OF PSYCHOLOGY 

you will reply; yet in ninety-nine cases out of a 
hundred you do not remember your name at the 
time. You have formed certain fixed habits in 
regard to the particular sound to which you answer, 
but in few cases does it occur to you that you have 
heard the name in the past. 

Many times we reproduce in imagination past 
content, without being aware that it is past content; 
the experience is mere reproductive imagination, 
not memory. The facility with which non-reminis- 
cent reproduction occurs is at the basis of a great 
deal of plagiarism in literature; an author imagines 
a situation or sentiment which is really an exact 
or approximate reproduction of something he has 
previously read in another author^s writings, but 
he does not remember it, and so the trouble be- 
gins. A striking example of this sort of reproduc- 
tion is found in a short story or miracle-tale by a 
well-known American author, who relates that the 
story came to him in a sort of dream at night. The 
idea and elaboration of the tale are so similar to that 
of one of Tolstoi^s short stories as to raise the pre- 
sumption that the American author, having read 
Tolstoi's "Two Pilgrims," at some earlier time, 
reproduced it in an altered form, and failed to 
recognize it. 



RETENTION, MEMORY, AND RECALL 177 

The important thing about memory is the factor 
of recognition by which the reproduced content is 
enriched. We have said enough to indicate that 
this factor involves or depends upon certain feat- 
ures of perceived time; its further treatment will 
accordingly be deferred to the chapter in which time 
is discussed. 

3. Recall 

Given the fact that a content once perceived 
may be subsequently imagined; to which fact in the 
abstract we give, as said above, the name retention, 
we inquire why the content is imagined — called 
back, or recalled, as it were— at one time rather 
than another; or we may even wish to know why or 
how it is recalled at all. A part of the mechanism 
of recall is understood, if imperfectly. 

In the first place, the very fact of retention im- 
plies a tendency to come back. Whatever content 
has been experienced may by virtue of that fact 
alone return later to consciousness. The expres- 
sion '* spontaneity of the image ^' has been applied 
to this recurrence-tendency, the expression figuring 
the image as an entity with an active force pressing 
it toward the field of consciousness. We might 
develop the analogy by likening consciousness to a 



178 A SYSTEM OF PSYCHOLOGY 

stage, of varying area, but strictly limited, on which 
a vast crowd of players are seeking to enter. Some 
of these players are continually sent on and oflF the 
stage by directing agencies, but if these agencies 
cease to operate, or leave vacancies, the images hav- 
ing the most energy at the moment will thrust 
themselves on. It is especially in dreams and rev- 
eries that content seems to revive in the way de- 
scribed by this highly artificial analogy. 

In the second place, content revived in memory 
or imagination tends unmistakably to disappear 
soon after its entry into the field of consciousness. 
It may be kept before consciousness for varying 
periods of time through the effect of associative 
factors, or in pathological cases the image may 
monopolize consciousness for long intervals; but 
normally it tends to fade soon after appearing. In 
the terms of the analogy, the players seem to be ex- 
hausted by the effort of their appearance before the 
foot-lights, and need to retire to some psychologic 
greenroom for long periods of recuperation. If it 
were not for this fortunate shortness of vitality of 
imaged content, the stream of thought would soon 
cease to flow, as in the pathological cases above 
mentioned. 

The most important factor in recall is association. 



RETENTION; MEMORY, AND RECALL 179 

The content of past experience is so linked together 
that given any perception or imagination-content 
before consciousness it tends to bring in certain 
other content. This Unkage is designated as asso- 
ciation. Because association is of wider interest 
than is its function in recall, we shall give it a chap- 
ter by itself. 



CHAPTER XII 

ASSOCIATION 
I. The Principles of Association 

Association is the organization of experience, 
by virtue of which the various kinds and parts of 
content constitute a whole; it is the functional inter- 
connection of the objects of experience as we find 
them; not a force or activity. The statement of 
the principles or laws of association is by no means 
an explanation of anything, but simply a convenient 
summary of observed facts. 

I. The Principle of Integration. 

The total content of consciousness under nor- 
mal conditions is unified or organized into a unity. 
The various factors which we distinguish are given 
not as distinct elements fortuitously collocated, but 
as inseparable parts of the total content. This 
organization or integration has two directions: (1) 
Organization in simultaneity, and (2) Organiza- 
tion in succession. 

(1) We find organization at any given instant in 

the content of consciousness. If we liken the total 

180 



ASSOCIATION 181 

content to a rope, a cross-section of the rope repre- 
sents the state of the content at any given time. If 
we analyze this cross-section of content we find it 
reducible to the factors already enumerated (sen- 
sation and relation, with feeling and possibly image; 
the association as content, is relational). We do 
not suppose that these elements originate individ- 
ually and then unite, like chemicals thrown into a 
beaker; we consider them as arising in the com- 
binations in which they are found, and likewise 
declining; by both processes modifying the com- 
plexes in which they exist. 

We find the cross-section of content made up of 
several smaller unities — again like the rope, al- 
though the rope strands are merely contiguous, 
while these complexes are more or less intercon- 
nected, the same element often forming an element 
of several. If you are looking at a rotating color- 
wheel, and also thinking of the end of the hour, the 
content of your consciousness is composed of several 
subdivisions somewhat like the following: A, A 
complex of color and sound sensations with rela- 
tions and images (which you call the color-wheel) 
with certain emotional factors, perhaps interest, 
perhaps ennui. These tend to form a special 
group, possessing an internal coherence not shared 



182 A SYSTEM OF PSYCHOLOGY 

with the other groups described below, although the 
emotional element, and perhaps some sensational 
elements, may be common. B. Your thinking of 
the end of the hour depends on the function of a 
specific group of content (mostly imaginative), both 
sensory and intellectual, with emotional coloring, 
perhaps of desire, impatience, or aversion, or per- 
haps the ennui above mentioned. Imagery of the 
length of time yet to elapse, of the occupations to 
commence, of the heat of the sun outside, and so on, 
may supply the nucleus of this division of content. 
C A third group, or set of groups, is composed of 
bodily feelings, with certain sights and sounds not 
involved in the first mentioned groups — the mov- 
ing of shadows across the wall; the buzzing of a 
fly; the pressure of the clothing on the skin; the 
warmth or chilliness of parts of the body; visceral 
sensations, thirst, and so on; with, perhaps, certain 
emotional coloring not germane to the other groups. 
Each of the three groups mentioned is separable 
under scrutiny into several subgroups^ The anal- 
ysis, or a stage in the analysis, of group C is obvi- 
ous. In group A the treatment is not so easy. 
Perhaps we find the visual factors forming the nu- 
cleus of one subgroup, and the auditory that of an- 
other, but in some cases it seems that the auditory 



ASSOCIATION 183 

and visual factors are united with each other as 
firmly as auditory with auditory or visual with 
visual. 

In many cases we find, before reaching the ulti- 
mate elements, peculiar small groups which are 
called fusions, in which several sensations of the 
same mode can be discriminated. Thus, the hue 
of the revolving wheel may be a fusion of several 
primary colors; purple is a fusion of red and blue; 
the taste of the lemon-drop in your mouth is a fusion 
of sweet, sour, and a slight bitter. It is a question 
whether we ought not to include under the term 
^^fusion'^ combinations not of the same mode, as 
warmth and touch sensations, taste, and smell. 

In applying the name " fusion,'' we mean to im- 
ply that while these combinations function as units 
in practically the same way as do elementary sen- 
sations, they can be perceived as complex, by atten- 
tive observation. In this analysis the complex con- 
tent changes: it is a commonplace that the taste of 
lemonade is not simply the taste of lemon jplus the 
taste of sugar, but has an individuality of its own. 
This change is readily made intelligible if we re- 
member that in analyzing a fusion we bring in or 
emphasize relations which were not previously in 
the content, or else were not vivid; and that in ex- 



184 A SYSTEM OF PSYCHOLOGY 

periencing separately the elements of the fusion, as 
the sour and the sweet, we have in the contents a 
different relational nexus, and perhaps, also, differ- 
ent imaginative sensory factors from those present 
when the fusion is experienced even with attempt 
at analysis.^ 

(2) We have said that content is organized not 
only in simultaneity, but also in succession; it is 
integrated in longitudinal as well as in cross-section. 
The present content is essentially connected with 
that of the future and of the past. Moreover, each 
group, subgroup, and element has an actual life 
history. No sensation, for example, comes into 
existence instantaneously; it rises, reaches a maxi- 
mum of intensity, and then falls back. So a cross- 
section of any portion of the content of consciousness 
at any time represents only a stage in its develof>- 
ment. In this the analogy to the rope comes up 
again; the rope is made up of fibres, each having a 
definite length, short as compared with the length 
of the rope; but here also the analogy fails, as there 

^ The student may be surprised at the way in which the 
^individuality" of the lemonade taste may be made to de- 
crease. Take a glass of lemon-juice solution and a glass of 
sugar solution, of such strength that when equal quantities 
of each are mixed in a third glass a good lemonade results. 
Then taste the three solutions in alternation, making careful 
comparisons. 



ASSOCIATION 185 

is nothing in the rope to represent the temporal 
development of the subgroups. 

It is clear that psychological research has a two- 
fold problem at any point which it attempts to in- 
vestigate from the side of content: first, to analyze a 
given content, and, second, to trace the development 
thereof. The solution of the second problem is 
much more difficult than that of the first, for it 
really involves the solution of the first for a number 
of successive stages. If I wish to study emotion 
of a certain type, for example, I must not only 
analyze such emotion at a given moment or stage, 
but must also make or assume analyses at several 
moments in its life history, in order to understand its 
development and the longitudinal connection of its 
elements. The same treatment should eventually 
be applied to the total stream of consciousness; by 
performing adequate analyses at enough points in 
the life history of the individual we might get a 
comprehensive view of the psychic life. 

II. The Principle of the Middle Term, or Medi- 
ate Association. 

Two contents or factors in content which are not 
strongly linked directly may be linked each to a 
third term, or they may be linked through several 
intermediaries: and this mediate linking of the two 



186 A SYSTEM OF PSYCHOLOGY 

may be more important practically than the direct 
associations with the intervening term or terms. 
If M and N are two factors in content which are so 
far apart in time that M has practically faded out 
before N commences to rise, but if P occurs while 
M is vivid, and is still eflFectively on the stage when 
N becomes vivid, the three may form a fibre in suc- 
cessive association, uniting M with N through P. 
The name ^*Bud^^ and the jaw movement of gum- 
chewing are, perhaps, associated in your experience 
not because you have heard the one and seen the 
other at the same time, but because each has been 
associated in simultaneity with some other feature 
or features of an individual. Other examples will 
readily occur to the reader. Emotional content is 
especially apt to form a third term in this way. 
Those contents which have been experienced to- 
gether under the influence of strong emotion are 
more firmly associated thereby, other things being 
equal, and what has been experienced with a certain 
quality of emotion at one time is associated medi- 
ately with what has been experienced at another 
time under the same sort of emotional conditions. 

III. The Principle of Intellectual Association. 

The association of two elements or groups of 
content is stronger in so far as a definite relation 



ASSOCIATION 187 

or system of relations is perceived as subsisting be- 
tween them. If I notice that two things are simi- 
lar or dissimilar in some regard, or if I notice that 
one immediately follows the other, or if I perceive 
or imagine that one is the cause of the other, or 
that they are spatially related in a certain way, 
these things are more strongly associated than if 
the relations had not been noticed. 

IV. The Principle of Redintegration. (Principle 
of Reinstatement; Principle of Associative Recall.) 

When any content appears in imagination or 
apprehension there is ipso facto a probability that 
the other contents associated with it will appear 
also: in other words, a total content tends to be 
reinstated as soon as a part of it is introduced. 
The events are analogous to what happens when 
you try to pull a weed out of a tangle in the water; 
you find that you pull out a large quantity of others 
which are ensnarled with it. 

There are several ways in which this revival of 
past content through association may take place. 

(1) The associated factor may reappear in the 
same organization as before. If you meet to-day a 
person whom you met yesterday, you may be again 
conscious of some of the circumstances in which 
you met him before. The stage setting, as it were. 



188 A SYSTEM OF PSYCHOLOGY 

in which he was placed is revived as soon as he 
reappears. In repeating the words of a poem the 
imagery and emotions appropriate to the words and 
phrases which have been associated with them come 
up in proper synthesis. Moreover, the successively 
associated factors are repeated in their former 
sequences; the words of the poem are recalled nat- 
urally in the order in which they have been linked 
in the text of the past experience. The series of 
words forming the poem are, as the result of the 
past experience, associated in a whole in which 
imagery and emotional coloring bind them together 
in multiple bonds. Words and phrases in one 
portion of the poem are so linked by intermediate 
terms and directly with phrases in other portions, 
that having once commenced the recitation of the 
poem we are in little danger of being carried off 
the thread into something else. But if we were 
restricted to associations between simultaneous or 
immediately successive factors, we would be apt, 
when we have recalled the line " lead kindly light,*^ 
to finish it up " of other days around me,^' and still 
more apt to finish " Yes, that was the reason (as all 
men know), in this kingdom by the sea, that the 
wind came,^' by adding *^up out of the sea, and said, 
'O mists, make room for me.'" 



ASSOCIATION 189 

In poetry the enveloping rhythm furnishes a con- 
tinuous bond in association which would operate to 
prevent transitions such as those we have just sug- 
gested; in some cases, however, the transitions from 
one text to another would not alter the rhythm, 
especially if it is a matter of diflFerent bits from the 
same poem. In prose, of course, there is nothing 
but normal mediate associations to prevent the va- 
rious texts we have memorized from being "pied'' 
in recall. 

The rhyme furnishes in some poetry an addi- 
tional means of association. Certain sounds are 
given by their position in the rhythmic structure, 
and, by repetition, an especial emphasis and dura- 
tion in consciousness, so that there is immediate 
association between one rhyme word and the ones 
preceding and following it. Rhymes, alliterations, 
and all such devices are to be considered as means 
for the production of associative bonds, tying the 
stanzas together in a more unified whole than 
would otherwise be achieved. They are not aes- 
thetic ends, but are mechanism for the production 
of ends aesthetic, or even practical, as in the jingles 
by which we manage to fix elusive facts of history. 

(2) The time order of the former content may 
be modified in the recall. The setting in which I 



190 A SYSTEM OF PSYCHOLOGY 

saw the person yesterday may not recur when I see 
or think of him to-day, but may come in afterward. 
On the other hand, things which were experienced 
in succession may be imagined or remembered simul- 
taneously, or when one is perceived the others are 
recalled simultaneously with it. After the child has 
experienced the sight of the medicine, followed by 
the taste, and perhaps subsequent nausea, the mere 
sight of the proffered mixture arouses coincidently 
the other factors. 

(3) Very frequently contents which have been 
mediately associated become immediately associ- 
ated through the dropping out of the middle terms 
or term. Seeing a load of coal put in suggests the 
sifting of ashes; hearing a huckster announcing 
soft crabs suggests finding a gold watch; yet the 
various terms which in the beginning mediated the 
association do not occur to me until afterward, if 
at all. This sort of modification of association by 
the elimination of terms is so common that it 
largely escapes our notice. 

V. The Principle of Relative Strength. 

We may say that the possibility of the reinstate- 
ment of any content through association with an- 
other content present to consciousness is propor- 
tional to the strength of the association, and that 



ASSOCIATION 191 

therefore if a given factor, M, is associated with two 
contents, P and Q, which are too different to come in 
together, the one most strongly associated with M 
will come. (The so-called principle of conflicting 
associations.) But if P is associated with M, and 
also with K, which is just disappearing, and with S, 
which is present throughout, whereas Q is asso- 
ciated only with M, P may be brought in, in spite of 
the stronger connection of M with Q than with P; for 
the other associations assist in reviving P. (This 
is sometimes called the co-operation of associa- 
tions.) We may illustrate by the poetical frag- 
ments given above: the Longfellow poem may be 
much more familiar to you than the one by Poe, 
and hence " the wind came up" more strongly asso- 
ciated with "from out of the sea" than with "out 
of a cloud by night." In that case, if some one 
should repeat to you " the wind came up, " alone, 
you would finish the line Longfellow- wise. When 
the earlier lines of the poem of Poe are given you 
too, you finish the line accordingly because of the 
co-operating associations of "out of a cloud by 
night" with these earlier lines. 

The concept of "strength" of association must 
be admitted to be very vague. After all, it is 
constructed, like the concept of retention, from the 



192 A SYSTEM OF PSYCHOLOGY 

fact that things do come back, and that they come 
back in specific ways, as we have been trying to 
show. When we say that M is more strongly asso- 
ciated with P than with Q, we mean simply that 
unless some other factor operates, M will call up P 
rather than Q, 

The strength of any association depends, like the 
retention of content, upon the vividness with which 
the associated factors are impressed, and on the 
repetition of the impressions in succession or 
simultaneously. This needs no extended discus- 
sion here. The strength of the association is also 
increased by each recall through the association; 
the oftener M calls up P, the more readily it will 
do so. 

2. Voluntary Recall 

We often make the attempt — successful or not — 
to recall some definite content. This attempt, or 
performance, seems at first inspection to be absurd. 
If I am not conscious of a given content how do I 
know what it is? The recall is actually set in 
motion, or we attempt to set it in motion, by a proc- 
ess which is naively described as ^'Thinking of the 
things we know to be associated with the required 
content," trusting to the associations to bring the 



ASSOCIATION 193 

required content before consciousness. But we 
ask: How do I know what is associated with the re- 
quired content, if I do not know what that content 
is ? And how do I manage to bring up the things 
associated with the required content ? 

The fact is that these contents are already there, 
or some of them are, and it is their presence that 
brings the desire for the sought factor. Some fac- 
tor, M, comes up, which is in a certain relation to 
something else, and yet the present factor and the 
relation do not bring up the missing one. So I 
attend to some other factor suggested by M, to see 
what it will suggest; if this does not suggest some- 
thing satisfying the relation, it may suggest some- 
thing which will make the proper suggestion. For 
example : I see across the room a man whose name 
I do not remember. The fact that I am approach- 
ing him calls up the impending salutation, and the 
relation of the visible man to a name; yet the name 
is not recalled. The appearance of the man recalls 
Mr. Blank, at whose house I was introduced to the 
man; I hold the idea of Mr. Blank and the meet- 
ing in consciousness, and these factors recall the 
joke Mrs. Blank made on the man's belying his 
name; still the name does not appear, although I 
am getting "warm.'' This incongruity of man and 



194 A SYSTEM OF PSYCHOLOGY 

name, if attended to, may suggest his voice, and 
then the name — Singer — may come up at once. 
This is a typical instance of voluntary recall, and 
the only voluntary element is the "holding of the 
attention on certain content," to get the maximal 
effect from its associations. 

Sometimes the factors on which the attention is 
held in voluntary recall are relations. Thus, in 
trying to think of a man's name the relation of 
rhyming with something may come up, and by at- 
tending to that relation a rhymed word will in 
many cases appear, and assist in the final solution 
of the problem. Sometimes we start with a num- 
ber of relations and seek that which will fulfil 
them; start with a concept, in short, and let it de- 
velop into an idea. This is conspicuously the case 
in the solution of riddles. 

3. The Probable Physiological Basis of Association 
The exact physiological bases of association are 
as yet unknow^n. We assume that there are some 
processes in the brain corresponding to these func- 
tions, but what they^are or where they are located 
has not yet been discovered. It has been quite the 
fashion to ascribe association to the formation of 
" brain-paths, " lines of conduction from one cell or 



ASSOCIATION 195 

group of cells to another; but this was intended 
only as a picturesque metaphor; for, taken liter- 
ally, it would imply a special cell or group of cells 
for each idea capable of being associated with an- 
other, or other absurdities which no psychologists 
or physiologists entertain. Some theorizers have 
assumed the existence of a special association cen- 
tre in the frontal lobes, but so far there is not much 
real evidence for the theory. 



CHAPTER XIII 

PERCEPTION 
I. The General Nature of the Content in Perception 

We have already indicated that perception com- 
prises more than intuition or direct apprehension; 
that is to say, that the content in perception in- 
cludes more than sensations and relations. Per- 
ception^ is the consciousness of a content which in 
usual cases includes (1) present sensations, (2) 
present relations interwoven with the sensations 
and other content, (3) imaginative content, and 
(4) emotional factors. With regard to the third 
category, we ought to say at once that by far the 
most important thing in the imagined portion of 
the content of perception of adults is conceptual. 
The merely sensuous imagery may play a part, but 
it is relatively unimportant in comparison with the 
systematized relationships in which the intuited 
content is placed. 

Suppose I stand some distance from a railroad 

track and observe a passing train: I obtain a com- 

^ ''Perception'^ is used loosely in common discourse for any 
sort of understanding or comprehension. We are using it here 
in a strict, technical sense. 

196 



PERCEPTION 197 

plex perception-content which it is worth our while 
to analyze. In the first place, there are the ele- 
ments of light and color. The locomotive, the cars, 
the smoke, the trees which form the background, 
are presented as an aggregate of many hues and 
shades. At the same time are presented sensations 
of other modes; the panting of the locomotive and 
roaring of the wheels and shriek of the whistle, the 
smell of the smoke, and the trembling of the ground. 
These sensations are only a small part of the total 
content. Not only do I notice the spatial relation 
of the colors — that the dark and shiny locomotive 
precedes the red cars, that the smoke hangs above 
the trees and spreads out — but I notice the likeness 
of the smoke to the clouds, the contrast between the 
red and the green of the trees, and so on. More- 
over, I am conscious that it is a passenger train, 
which means, probably, that I imagine people 
within it: I imagine the wheels turning, although I 
cannot see their rotation; I image other features 
according to my habits of thought. Certainly, 
whatever I perceive of a sensory nature, beyond a 
few patches of color and a few sounds and smells 
and the vibration, is imagined. 

More important than the intuited content, or the 
imaged sensory content, is the fact that I recognize 



198 A SYSTEM OF PSYCHOLOGY 

the object as a railroad train; I am aware of its 
relations to iron tracks, stations, transfer of pas- 
sengers, purchasing of tickets, and numberless other 
details, some of which, like the passengers inside, 
may be imaged, but the greater number of which 
are not. On account of this conceptual synthesis 
of the content, my train as I perceive it is vastly 
different from the train a savage would perceive 
from my view-point, although he would experience 
the same sorts of sensations and the same pre- 
sented relations as I do. So, too, the train as the 
content of the railroad man or of the farmer would 
differ largely from mine, because in each case a 
different set of relations would be emphasized by 
the individual's past experience, and be aroused to 
unite as a concept with the intuited factors. 

The function of the concept in perception is 
sometimes called apperception. The concept and 
the imaged sensory factors connected with it are 
called the apperception mass, and the directly ap- 
prehended sensations and relations the apperceived 
factors. These terms are now falling into disuse. 

The concept is built, developed, and extended, 
by experience. Any new perception is apt to mod- 
ify the concept which functions therein. The 
first time an individual rides on a train, which be- 



PERCEPTION 199 

fore he has merely seen — and heard — from a dis- 
tance, he apprehends a lot of new relations which 
thereafter recur in the concept. If perchance he 
sees some one run over, the train is perceived with 
new elements of relation, and henceforth all trains 
will be perceived in the light of a concept modified 
by those relations. 

Changes in the concept may take place also 
without perception; when the sensory content 
which fills out the concept and makes it concrete 
is only imaged. When, for example, I speak to 
you of trains, you imagine them; your concept at- 
taching itself to the sensory content which you call 
up, just as if it were apprehended in reality. If 
then I tell you of the running over of some one, or 
explain the problems of maintaining equilibrium on 
curves, or providing suflBcient elasticity to allow 
starting and stopping, the imaged content takes in 
new details, and the modified concept will govern 
your next perception of a train. 

We may reach a stage of conceptual development 
in which concepts are modified without the neces- 
sity of filling in, even imaginatively, with sensory 
content. New relational factors are learned, usu- 
ally by inference, and these are amalgamated with 
the concept already in existence: or the process 



200 A SYSTEM OF PSYCHOLOGY 

may be one of elimination, certain supposed prop- 
erties of a certain thing being found not properly 
belonging to it, and the concept being contracted 
accordingly. It is difficult to show instances of 
this purely intellectual modification of concepts in 
every-day life (although it undoubtedly occurs 
there), but in science the process is clearly exhib- 
ited. The atom, for instance, was conceived with 
an approach to adequacy, and as new facts 
were learned the concept was modified accordingly, 
until it has become vastly different from that held 
by scientists twenty-five years ago. Yet sensory 
imagination plays little part in this readjustment, 
being more a disturbing factor than otherwise. In 
less abstruse cases, where imagination might have 
a role, the scientist economizes energy and in- 
creases accuracy by leaving it out.^ 

The development of perception is, therefore, in 
reality, the development principally of conception. 
The sensory factors are very simply controlled, and 



^ We may distinguish three types of conceptual modifica- 
tion, which possibly correspond to stages of mental develop- 
ment. These stages are: (1) The perceptual, (2) the concrete 
imaginative, and (3) the conceptual modification of con- 
cepts. Possibly animals are restricted to the first type, but 
of this we have no proof. In the case of adult human beings 
the first type rarely occurs pure, but undoubtedly many per- 
sons never attain in the slightest to the third type. 



PERCEPTION 201 

only a small amount of experience is needed to 
make them practically as perfect as they ever may 
be. The individual is endowed by his parentage 
with his sensory apparatus; it is developed in part 
through the demands made upon it by his experi- 
ence, but largely through the general development 
of the body, just as the hair grows. A little prac- 
tice is needed to direct, focus, and converge the 
eyes properly, but these adjustments develop in 
the individual largely of themselves, demanding 
only use to fix the development. The child of a 
few years is equipped sensationally as well as he 
ever will be, and much better than he will be in 
adult life. 

2. Perception, Illusion, and Hallucination 

Perception may be "right" or "wrong." The 
incoming sensory content may be united with the 
proper concept, or it may be united with an egre- 
giously inappropriate concept. The former case, 
where the perception is " right/' we are accustomed 
to call true or normal perception, and the latter case 
we call illusion. To take an extreme case: a 
sheet is hanging on a bush in the dark, and some 
one seeing it unites the visual appearance with his 
concept of a ghost: his perception is illusory, yet 



202 A SYSTEM OF PSYCHOLOGY 

he may receive sensory and relational intuition- 
content practically agreeing with that of another 
person who unites it with the appropriate concept 
and perceives truly. 

The freshman who looked at the page-heading 
in my copy of the Critique of Pure Reason and 
exclaimed in amazement, "Transcontinental dia- 
lect! What in the dickens is that?/' probably re- 
ceived from the printed words sensations not very 
different from those I received; but since one, in 
reading, notices but a part of the letters in a word, 
imagining or dispensing with the rest, the fresh- 
man's unfamiliarity with the transcendental dia- 
lectic resulted in the noticed letters calling up the 
concepts associated with them in his experience. If 
you see a man on the street, and say, " Ah, there is 
Richard Roe; I must speak to him about that 
book," and then find on overtaking him that it is 
not Roe at all, but John Doe, who scarcely re- 
sembles Roe on close scrutiny, your mistake lies in 
that to certain sensory factors intuited you added 
the imagined facial expression, etc., of Richard 
Roe, and the concept you have formed of that 
gentleman. 

The contrast between perception and illusion 
disappears when we examine them closely. The 



PERCEPTION 203 

extreme cases we have instanced, where the con- 
cept is hopelessly inadequate, are few in compari- 
son w^ith the cases in which the inadequacy is not 
so pronounced. Many persons at the present 
time conceive a trolley-car as dragged along by the 
trolley, vaguely supposing that the "current'' in 
the wire carries the trolley along with it, as the 
cable "grip'^ is carried by the cable. When such 
a person has found out the way in which a street- 
car is actually propelled, the content of his percep- 
tion of a car is appreciably changed; and yet the 
error is of no practical consequence to the mistaken 
man as long as he does not attempt to fill a posi- 
tion as a carman. On the other hand, a slightly 
inadequate perception of a car as regards its speed, 
or of an invalid as regards his condition, may have 
the most serious consequences. Perhaps the truest 
statement would be that none of our conceptions and 
perceptions are quite adequate, but some are near 
enough to adequacy for practical purposes. 

One special type of "false" perception has re- 
ceived the name of hallucination. In this the in- 
tuited sensational factor is reduced to a minimum, 
or at least is not of any practical consequence in 
the total perception. The essential sensory fac- 
tors are all supplied by imagination, but the com- 



204 A SYSTEM OF PSYCHOLOGY 

plex is mistaken for, or at least has the apparent 
character of, reality. Hallucinations occur to al- 
most all of us in what we call dreams, and some- 
times in waking life, but waking hallucinations are 
usually attendants of mental disease. 

Hallucination and illusion are to be distinguished 
from pseudo-hallucination and pseudo-illusion. 
Pseudo-hallucination is often found in dreams, 
where the content has the semblance of perception- 
content, except that the dreamer is distinctly con- 
scious that it is a dream, and not real. So, in wak- 
ing life, there often occur experiences which have 
many of the marks of perceptions, but which we 
know are imaginations. There is something about 
the experience or the content which gives the lie 
to the impressiveness of the other factors. The 
semblance of reality produced in pictures and on 
the stage is to be classed as pseudo-illusion. The 
familiar geometrical illusions, on the other hand, are 
true illusions in most cases, for the semblance has 
all the characteristics of true perception-content, 
in spite of the fact that we know it is not. We have 
to do here with a percept and an additional con- 
cept which do not fuse or unite. ^ 

* Hallucinatory perceptions must be distinguished from 
subjective sensations, secondary sensations, and after images, 



PERCEPTION 205 

3. The Determination of Perceptual Truth and Falsity 

The discussion of illusion brings us to the con- 
sideration of the criterion of truth in perception. 
Here we find two questions. First: When, and 
in how far, is a perception true? and second: How 
do we decide whether a sensation is true or suffi- 
ciently near the truth? As a matter of fact, the 
grounds on which we decide practically the truth 
of a perception are by no means those which would 
be assumed for the philosophical justification of 
the decision. The statement of the grounds on 
which we actually judge the validity of a perception 
does not cover the grounds on which a thoroughly 
adequate determination could be based. 

There are two practical tests of truth and falsity. 
The first may be called the social test If my per- 
ception is illusory or hallucinatory, it is in most 
cases shared by no one else, and, conversely, if it is 
shared by no one else it is an illusion or hallucina- 
tion. If, for example, you see a translucent hand 
beckoning from the door-way, and others in the 

and from the phenomena in certain pathological cases where, 
for example, the smell of a certain odor is persistently present 
to consciousness, without the normal stimulation. All these 
cases are of present sensations due to definite sensory processes 
in the sense mechanism. 



206 A SYSTEM OF PSYCHOLOGY 

same room see nothing of the kind, you know that 
you have an hallucination, and if you are wise will 
consult a competent physician. If you hear some 
one talking, whereas other persons in the same room 
hear only the trickling of water from a leaky fau- 
cet, you conclude that you were mistaken in your 
perception. 

The social test is not thoroughly trustworthy. 
Frequently your perceptions are right and those of 
your companions wrong. The obstinacy of one 
man in insisting that he hears the crying of a child, 
when the others are equally confident that the 
sound is the moaning of the wind in the trees, 
saves the child's life. It is possible, also, for a 
number of people to be simultaneously illuded, as 
a number of " authentic '^ ghost stories show. Per- 
sons of the same general type and training placed 
in similar circumstances will perceive in much the 
same way, and there is nothing surprising in the 
fact that a number of people will bring up 
wrong concepts of approximately the same sort, if 
the conditions are about the same for all. For 
example, if several persons are expecting to see a 
ghost, that is, if the appropriate concepts and images 
have been recently and vividly attended to, the 
sensational data which suffices to revive and unite 



PERCEPTION 207 

with the ghost-concept of one may suflGice for the 
others. 

The important practical test is your own further 
experience. If the pin you see on the floor can be 
picked up, and stuck into something, it is still con- 
sidered as a pin. But if it fails to give all the sen- 
sations (visual, tactual, etc.,) expected from a pin, 
you conclude that your first perception was wrong. 
If the man you take for an acquaintance does not 
respond to your words in the way you expect, you 
conclude that after all he is some one else. And 
so on. A large part of the perceptions of our ex- 
perience are proved inadequate by the further 
transformations of the content, and are revised 
accordingly. 

The philosophical question as to the real nature 
of truth arises from the consideration of the possi- 
bility that we may be more or less deluded in our 
daily life without becoming aware of it. So many 
times we act on a misconception, and yet our action 
fits the case suflSciently well, that we wonder if any 
of our tests give us anything really fundamental. 
One school of modern philosophy insists that any- 
thing is true in so far as it works, and no farther; 
that truth is just the fact of standing the practical 
test. An older conclusion is that a perception 



208 A SYSTEM OF PSYCHOLOGY 

may be true or false quite regardless of my action 
on it; that when I perceive a bottle in the road in 
the moonlight, it either is or is not a bottle, even 
if I do not get off my horse to investigate it. But 
no one has been able to propose a really satisfactory 
explanation of the nature of truth. 

4. The Causes of Illusion 

The immediate cause of illusion is not different 
from that of normal or correct perception. The 
imaginative content which is in the one case in- 
adequate, and in the other case adequate addition 
to the intuited factors, is in either case revived 
through association. It is not necessary that the 
reproduced content should be previously associated 
with the directly presented content in the perception; 
it may be called up through an associative linking 
with some other content factor in consciousness. 
Thus, you take the shadow by the roadside for a 
robber, not because that particular impression of 
light and shade is essentially connected with the 
figure of a man, but because your consciousness is 
already filled with imagination of brigands and 
hold-ups. In commoner cases, you misread a 
printed word, or mistake spoken words because 
something you have just read, or heard, or thought 



PERCEPTION 209 

of is associated with the idea corresponding to the 
misreading or mishearing. 

In normal perception, you make out the cold 
cylinder you grasp in the darkness of the garden 
to be the hose because you imagined it to be there 
(or possibly you conceived it as there) before you 
touched it; if you did not, it gave you a shock, and 
the perception came more slowly after additional 
factors had been experienced. Waiting for the 
train, the distant whistle is easily recognized, when 
otherwise it would have passed for one of the feat- 
ures of the storm roaring about you. In reading, 
the words are recognized by the appearance which 
you sense in an inadequate way, assisted by the 
images excited by the preceding words and sen- 
tences. 

Association directly between the reproduced 
factor and the intuited factor of the perception con- 
tent is an important feature in the greater part of 
our perceptual life. Experience is a constant suc- 
cession of perceptions whose contents are unex- 
pected until they occur, and the imaginative parts 
whereof are not contributed from the just-preced- 
ing, or contemporaneous contents. The seen or 
otherwise intuited impressions call up the imagery 
associated with them from the past, and it may be 



210 A SYSTEM OF PSYCHOLOGY 

adequate to the occasion, or it may not. The notes 
of the flute which fall upon your ear from the next 
house are perceived as the sound of that empty- 
toned instrument although you had not been think- 
ing of flute or flute-tone until these notes smote 
your ear. The spider crawling on your knee may 
have been entirely unexpected until he met your 
eye, and yet you perceived him immediately. The 
sound of some one shutting the door, which turns 
out finally to have been the creaking of your chair, 
was not perceived wrongly because your conscious- 
ness was filled with the idea of some one entering 
the room, but because that particular sound was 
associated in your past experience with the other 
sensations from shutting a door. 

In determining the definite perception based on 
a given intuited content, the factors we have earlier 
described as governing the " strength ^^ of associa- 
tion and likelihood of recall play a large part. If a 
certain sense-content is strongly associated with 
certain other factors, either through repeated ex- 
perience of them in conjunction, or because of the 
recency or impressiveness of such an experience, 
that sense-content will tend to call up those factors 
regardless of whether they are the right or wrong 
things at the time. Moreover, the mere recency. 



PERCEPTION 211 

frequency, and vividness of past experience of a 
given content which is at all capable of assimilation 
to intuited content, increase the probability of its 
being revived by the intuited content, in accordance 
with the principles of retention and recall. The co- 
operation of associations is also of importance in 
many cases; if you notice the peculiar noise, and 
at the same time notice the movement of your body 
in your chair, you will be less apt to perceive the 
opening of the door, although the sound alone might 
have called up that illusory perception. 

Fine discrimination of sensations favors correct 
perception. The creaking of the chair was not 
precisely like the sound made by the opening of the 
door, so that the presence or absence of the illu- 
sion depends, in part, on the delicacy with which 
auditory differences are apprehended. In so far 
as sensory complexes seem alike they tend to call 
up the same associated factors, because the features 
of the contents which are noticed are associated 
with these factors; and in as far as the contents are 
discriminated, that is, in as far as other factors than 
the common ones are noticed, they tend to call up 
their special associates. 



212 A SYSTEM OF PSYCHOLOGY 

5. Space Perception 

In the analysis of perceived space we find one of 
our knottiest, but most interesting, problems. The 
history of philosophy includes much discussion of 
the question whether space is an actual external 
reality (the a posteriori theory), or whether it is 
something mental — a "form'' in our minds, sup- 
erposed on the world in perceiving it — (the a priori 
theory). The discussion of this question has really 
little to do with experience or its content, being 
based on conventional definitions of "mind" 
"external world" and other terms, much as the 
moves in a game are determined by rules; but it 
has had an unfortunate influence on attempts at 
psychological analysis. 

We must start from the fact that there is in our 
perceived content a factor which is practically the 
"space" of common parlance (not the "space" of 
the mathematician or metaphysician), and attempt 
to analyze this factor. 

The line of opposition has been drawn in the 
past between the "nativistic" and the "genetic" 
theories of space perception. In large part, the 
controversy between those holding these two views 
has been an unwitting discussion of the a priori- 



PERCEPTION 213 

a "posteriori question, complicated by the question 
whether we have to learn, as individuals, to perceive 
space, or whether we perceive it instinctively. In- 
volved in the controversy is the still further ques- 
tion whether space as perceived is sui generis, or 
whether it is constructed in some way out of ele- 
ments which are non-spatial. The genetic view 
insists that we learn to perceive space, and is usually 
a prioristic: the nativistic view holds to instinctive 
space perception, and may take either the a priori 
or the a posteriori tack. The apriorists, of course, 
believe space to be sui generis; the aposteriorists, 
whether nativistic or genetic, may take either side 
of this latter question. 

While our business here is primarily the analysis 
of the space-content, keeping clear of the meta- 
physical problems as far as possible, we shall not 
hesitate to assume that we as individuals learn by 
experience to perceive space in its detailed form, 
although a part of our perceptive ability is native 
or instinctive. This, however, is nothing but as- 
sumption, and our suggestions as to the probable 
development of space-content must be understood 
in the light of that fact. 

The characteristic thing about the space-world 
is that everything in it stands in definite and peculiar 



i 



214 A SYSTEM OF PSYCHOLOGY 

relations to everything else therein; relations which 
are analogous to some found outside of the space- 
world, but which are characteristically different 
from them. These space relations we recognize 
when we refer to distance, direction, contiguity, 
intervening objects, and other characteristic features 
of the spacial factor of our content. 

In addition, space depends on the relation of 
magnitude, which is found also in non-spatial con- 
tent, and likewise upon the universal relations of 
similarity, difference, etc.; but these are not, prop- 
erly speaking, factors in space. 

Space relations can be intuited only as founded 
upon the extensity-character of sensation. Whether, 
having been perceived, they may be imagined — 
may form part of a conception — without the imaged 
sensation, is another, and questionable, matter. 
Our own opinion is that when space is strictly con- 
ceived it loses its true content-character, and be- 
comes merely a mathematical system of relations 
w^hich is marked by a correspondence to the space 
of perception and imagination. 

The difference between extensity and extension; 
between the mere sensational volume and space, is 
this: as soon as you begin to discriminate extensive 



PERCEPTION 215 

parts within a sensation, or mass of sensation, you 
have space. The perception of the extensity as 
divided; as having one part set off against another 
part — the perception of extensity in relation — is 
the perception of extension or space. 

In gustatory and olfactory sensation we have no 
distinction of extensive parts, and in consequence 
no gustatory or olfactory space. These sensations 
may be more or less massive or extensive, but that 
is all. The same is true of sounds; the volume of 
a tone may change, but there is no space-character 
to the tones because there is no relation of extensive 
parts of any tone, but simply a relation of extensities 
of different tones. We may say, with great proba- 
bility of correctness, that if we were restricted to 
these sensations there would be no space in the con- 
tent of our perceptions. 

Vision and touch supply the necessary conditions 
for the perception of a space-world. In these senses 
we have extensive magnitudes which are not homo- 
geneous, but which are differentiated by local signs. 
One extensive portion of sensation, (if of sufficient 
magnitude), is immediately different from other por- 
tions, and hence we may believe that an animal hav- 
ing only one of these sorts of sensation, or any sort 
of sensation in which extensity and local signs are 



216 A SYSTEM OF PSYCHOLOGY 

developed, perceives space, although the space 
may not be very complex.^ 

The fundamental spatial relation seems to be 
betiveenness. This differs essentially from the mere 
intermediacy of other continua, although we com- 
monly represent all sorts of intermediacy in the 
spatial terms; as, for instance, a series of values by 
points on a straight line. The perception of be- 
tweenness in space may depend on the perception 
of time; that is, when an object moves over the 
skin or retina it occupies a certain position between 
the moments at which it occupies other positions; 
and by repetition of these experiences the spatial 
betweenness of the various points is brought to 
perception. Yet it is not at all certain that the spa- 
tial betweenness may not be perceived as directly 
as the temporal. 

The perception of the intermediacy of local signs 
in an extensity continuum furnishes the primary 
datum of space. The relation of direction may be 
reducible to these factors plus the implication of 
motion; but this is a mere conjecture. The oc- 
currence of the same local sign in two different series, 
as a stimulus moves in actually different directions 

^ For the "musical" ear the series of pitches may therefore 
form a rudimentary space-system. 



PERCEPTION 217 

over the sensitive surface, may be the first clew to 
difference of direction. 

Distance is primarily the amount of difference 
in local sign between two points; this corresponds 
roughly to the least number of local sign differences 
discriminable between the two points. You will 
find for example, on the skin, that two points appear 
separated by an interval approximately propor- 
tional to the number of different points discrimin- 
able in the straight line between them. This is 
why the points of a pair of compasses or scissors a 
quarter of an inch apart appear more widely sep- 
arated on the finger-tip than on the arm, and still 
more widely separated on the tip of the tongue. 
Of course, if no points are discriminable between 
two given points, they will be perceived as one 
point.^ 

So far we have considered only the factors which 
enter into space of two dimensions, that is, of sur- 
face. An animal endowed with touch or sight, or 
both, but with no sensation of movement, would 

^ An interesting experiment may be made by drawing the 
points of a pair of compasses across the face from side to side, 
allowing one point to pass above and the other below the 
mouth, and observing the apparent variation in the separation 
of the points when the distance between them is constant. 
Also, try drawing the points abreast down the arm, or down 
the leg from knee to ankle. 



218 A SYSTEM OF PSYCHOLOGY 

have experience of a space in which sensations ap- 
peared, moved about, and vanished; but the re- 
moval of the stimuli from the skin would simply 
cause the sensation to be unperceived, and stimuli 
at greater or less distances from the eye would sim- 
ply give sensations of less or greater area. The 
animal with touch and sight would probably per- 
ceive two spaces, for the chance that he would iden- 
tify his tactual and visual surfaces is slight. But, 
given the power of sensations from the movements 
of the sense-organs and members of the body, and 
unified space perception in three dimensions be- 
comes possible. 

It is scarcely probable that muscular sensation 
by itself can give space-content. The only between- 
ness of such sensation is the temporal betweenness, 
and its function in the production of space-content 
can be only secondary. But it does help to de- 
velop our space-content in a very important way, 
the outline of which is probably as follows. By 
moving one member (as the finger), over another 
member (as the hand), we acquire the connection of 
the temporal series of muscular sensations with the 
motion or series of positions in tactual space on the 
hand, and the continuous stimulation of one spot 
on the finger. By moving the finger over some ex- 



PERCEPTION 219 

ternal object we obtain the same series of muscular 
sensations, with the same sort of stimulation of the 
finger. The result is the conception of a surface 
over which the finger moves in the same way as it 
moves over the hand; the temporal series of mus- 
cular sensations having become associated with a 
series of positions in space, (tactual sensation ex- 
tension), muscular series which do not rouse the 
tactual series suggest series of positions in addition to 
those in the tactual field; hence space is immensely 
multiplied in extent. At the same time, since the 
same series of muscular sensations may condition 
a movement in tactual space and a movement in 
Tisual space, and the connection of two such series 
is invariable, the two are identified as a mere matter 
of mental economy; that is to say, tactual space is 
identified with visual space. 

If the above were the whole story, space as per- 
ceived would still be a matter of surface only. The 
feature of tactual-muscular perception which brings 
"depth" into space is this: a series of muscular 
sensations not accompanied by a series of tactual 
sensations (the finger moving through the air) may 
end in conjunction with a definite tactual sensation, 
and in fact we can put no limit to the number of 
different series which may terminate in conjunc- 



220 A SYSTEM OF PSYCHOLOGY 

tion with a sensation of practically any local sign. 
Here we have the primary factor in tri-dimensional 
space; series of positions, of which one or at most 
two lie in the given surface. Finding no definite 
limit to the number of series terminating at any 
position, the step to the conception of an infinite 
number is easy. In visual perception we have 
similar conditions, in that certain series of muscular 
sensations correspond to series of positions in the 
visual field, while certain other series correspond 
to a single position. 

It is not necessary to assume that the individual 
has to go through the stages from " blooming buz- 
zing confusion^' through two-dimensional space per- 
ception to tri-dimensional. It is not necessary to 
suppose that the infant's perceived space is other 
than tri-dimensional from the first. But without 
doubt the space relations are at first rather vague 
and simple, until the discrimination of local signs, 
and their connection with muscular sensations 
clears up and amplifies the content spatially as the 
child's motor processes develop and receive exer- 
cise. If, however, the individual does not perceive 
space instinctively, it seems quite possible for the fac- 
tors mentioned to bring the necessary relations to his 
consciousness, and build up the percept of extension. 



PERCEPTION 221 

We may describe a few experiments illustrating 
the co-ordination of visual and tactual space with 
muscular sensations. Hold before one eye a prism 
with large side, but narrow base, turning the base 
either to right or to left, and closing or covering the 
other eye. Better still, have a prism or a pair of 
prisms set in a spectacle frame, thus permitting the 
use of both eyes, and supporting them while leav- 
ing the hand free. On looking through the prism 
at any small object placed before you on the bare 
table, the object will in appearance be displaced to 
one side. Keeping your hand out of sight by your 
side until the moment of trial, make a rapid stab at 
the object with you forefinger. You will find that 
the finger strikes to one side of the goal. Keep on 
trying, and, in the course of a few minutes, you 
will find yourself able to hit the mark fairly well. 
Now remove the prism from the eye and repeat 
the trials, and you will find that you now make 
misses on the other side of the target, and require 
some practice to get back to your normal co-ordina- 
tion again. 

Suppose, looking through the prism, you touch 
your hand or arm with a pencil; or, better still, 
have some one else do the touching. The tactual 
and the visual spaces no longer seem the same, 



222 A SYSTEM OF PSYCHOLOGY 

but a little practice will bring them together as 
before. 

An interesting experiment, named after the 
philosopher who gave the earliest extant descrip- 
tion of it, "Aristotle's Experiment/' has been re- 
ferred to in 2 of Chapter IX. If the first and second 
fingers are crossed and the Y so formed is rubbed 
in the crotch with a pencil or rod, the rod feels 
double. The effect is still more surprising if the 
crotch of the crossed fingers is touched with the tip 
of the tongue or point of the nose; you can hardly 
fail to have the distinct perception of a forked 
tongue or bifurcated nose. But even this illusion 
can be destroyed by continued stimulation under 
visual control. 

Although space relations may be in the first in- 
stances — and later also — intuited just as are sensa- 
tions, they are in a great part of our perceptual ex- 
perience purely ideal; they are reproduced in the 
content through their association with intuited or 
reproduced sensory data. This is true, at any rate, 
in the visual perception of space, and there we know 
rather definitely what the factors are which are 
associated with the relations. 

Direction, that is, the angular estimation of space 
position with regard to the body or eye as a centre. 



PERCEPTION 223 

is indicated by retinal local sign, in conjunction with 
the muscular sensations coming from the ocular 
apparatus and the muscles of the body, especially 
the neck. Simultaneous stimulation of different 
spots of the retina gives localization in different 
directions, as do successive stimulations of one spot 
if certain muscular sensations intervene. By the 
specific muscular sensations intervening between 
the successive occupancy of one spot by two stimuli 
the angle between the two is estimated; that is, 
the relative direction of the two from the eye. 

Distance from the eye is indicated by a number 
of signs, which may be effective singly or in co- 
operation. These factors are (1) light and shade 
(chiaro-oscuro), (2) definition and color (aerial per- 
spective), (3) size (linear perspective), (4) angular 
perspective, (5) convergence and accommodation, 
(6) binocular disparity, and (7) parallax. 

(1) Objects in advance of others throw shadows 
across them, the direction of the shadows depending 
on the direction of the source of light. Often the 
depth of shadow corresponds to the degree of re- 
lief. A curious effect may be obtained from an in- 
taglio, obliquely lighted; it will appear at times to be 
a cameo, with the light coming from the opposite 
side. A little study will show you that the lights 



224 A SYSTEM OF PSYCHOLOGY 

and shadows of an intaglio do correspond approxi- 
mately with those of a cameo, if the two are lighted 
obliquely from opposite sides. How large a part 
chiaro-oscuro plays in visual perception may be il- 
lustrated by making a negative print of a portrait, 
and comparing it with the positive print. The re- 
versal of light and shade makes the picture surpris- 
ingly different. 

(2) Objects at a considerable distance from the 
eye are blurred through the irregular refraction of 
the air, and they likewise are tinged with color by 
the atmosphere. "Dim distance'' and "purple 
peaks," indicate the practical importance of this 
factor. The blurring of distant objects is easily 
noted in nature, and its representation is frequent 
in paintings. The absence of the customary tint- 
ing distortion, as in the Rockies, where the air is 
fairly pure and homogeneous, gives rise to ludicrous 
mistakes on the part of those unused to such con- 
ditions. The author once heard a tourist insist that 
he could easily walk in an hour to the base of the 
mountain range at which we were gazing; the range 
being really more than forty miles distant. 

(3) As an object recedes from the eye its retinal 
image becomes smaller; all lines connecting char- 
acteristic points in the image become shorter. It 



PERCEPTION 225 

follows, that if we know what size the object would 
appear when near, we have in this some information 
as to the distance from the eye at any time. 

(4) The form of an angle gives some information 
as to the relative distance from the eye of parts of 
the surface bounded by the lines composing it, pro- 
vided we know what the angle is really — that is, 
know its appearance from a certain position. A 
rectangular table top, viewed from a point not in a 
plane passing through the centre of the rectangle and 
perpendicular to one side, appears a rhomboid, and 
conversely, to represent a rectangular surface looked 
at obliquely a painter employs a rhomboidal figure. 

(5) The eyes must turn inward more strongly 
to look at a near object than at a far object. Like- 
wise, they must accommodate, that is, change the 
shape of the lens by muscular action for the near 
object. The sensations of these muscular adjust- 
ments give immediate information as to relative 
distances of objects fixated. Hold up your pencil 
a foot or so before your eyes and fixate alternately 
the point and a spot on the wall in line with it; 
you will find that the convergence and accommoda- 
tion sensations are quite intense. 

(6) Since the two eyes look at the presented scene 
from two different points of view, their images do 



226 A SYSTEM OF PSYCHOLOGY 

not exactly agree. This disparity of the images of 
the two eyes is turned to practical account in the 
stereoscope, which presents two slightly different 
pictures to the eyes. Since the pictures are origi- 
nally taken by a camera with two lenses, from two 
points of view corresponding to those of the eyes, the 
stereoscope reproduces the binocular disparity of a 
natural scene. The depth given by a stereoscope 
view is a demonstration of the importance of the 
binocular disparity sign in visual perception. 

(7) When you move your head laterally, the view 
before you changes slightly. An object may be hid- 
den behind another when the head is in one posi- 
tion, and emerge when the head moves far enough 
to one side. An object not hidden by a nearer 
one apparently moves closer to or farther away 
from it. The relative amount of parallactic dis- 
placement indicates the relative distances of the 
objects. 

Auditory sensations are localized in the space 
perceived through the visual, tactual, and muscular 
mechanisms, but not localized accurately. We can 
usually tell the side from which a sound comes 
by the difference in intensity for the two ears; and 
we may make a lucky guess as to its general direc- 
tion, especially if allowed to turn the head while 



PERCEPTION 227 

listening.^ In general, however, we attach the 
sound to the seen, felt, or imagined object which 
seems an adequate cause of the sound; hence the 
success of the ventriloquist. There can be no 
direct spatial reference of auditory sensation; a state 
of affairs which is puzzling until we reflect that 
the actual direction from which the sound ap- 
proaches can make no difference in the local sign 
of the sensation. ^ 

6. The Perception of Things 

The reader has doubtless been somewhat sceptical 
during our exposition of the content of perception. 
Sensations, relations — these are all very well, and 
there is no doubt that we do perceive them, but the 
important features of the world about us do not 
seem to be exhausted by this simple list. We per- 
ceive thingSy in which certain qualities inhere, and 
although one may be persuaded that the qualities 
are sensations, and that the things stand in percep- 
tible relations to one another, he can only with 
diflSculty be convinced of the necessity of abandon- 

^ Experiments seem to demonstrate that under certain 
favorable conditions the difference in phase of the sound- 
waves affecting the two ears (when one ear is nearer the source 
of sound), may assist in the determination of the direction 
from which the sound comes. In this case the subject is, of 
course, unaware of the difference itself. 



228 A SYSTEM OF PSYCHOLOGY 

ing the things themselves. Nor would we desire to 
convince him of such necessity. We have simply 
labored to show the student of what stuff the things 
he perceives are made, without attempting to prej- 
udice his view as to whether this world of things 
is entirely within himself, as Idealism and Material- 
ism teach, or whether the conditions are as common- 
sense assumes them to be. 

The nature of perceived objectivity offers a prob- 
lem for analysis which is simple as compared with 
some of the other problems of content. Assuming 
the perception of space, we find the fundamental 
feature of thinghood in the location of one sensory 
quality or group of qualities in the same space with 
another. It is very probable that an animal re- 
stricted to one mode of sense would not be able to 
perceive "things'' as we do. He might perceive 
spatial relations, but they would be comparable 
to the spatial relations we perceive in a picture. 
Allow him, however, the opportunity to identify 
visual sensations with a definite portion of tactual 
space, or vice versa, or to identify muscular sensa- 
tions with parts of either space, and all the essen- 
tial features of perceived objectivity are present. 
The "thing'' which we perceive is just the coinci- 
dence of sensations of diverse modes in definite 



PERCEPTION 229 

space relations, and involved in the manifold of 
other relations component in content. When we 
become metaphysical, we invent something called 
"substance'' or "matter'' to act as a mystic cause 
for this coincidence, but if we did not have the 
experience of thinghood, substance would never 
have been invented. The psychological problems 
involved in the construction of such a concept as 
that of substance, a concept which in itself is an 
experienced content, but which represents or refers 
to the transcending of experience, introduce no 
new difficulties, but belong to the mountains of 
details upon which we cannot touch in this outline. 

7. The Perception of Time 

In the field of time perception we find again the 
division between the apriorists and the aposterior- 
ists, but no real genetic theory of time has been 
constructed, nor has any one proposed a plan of 
time-content reduced to non-temporal factors. As 
in the case of space, we may assume with proba- 
bility that we learn, in part at least, to perceive 
time, but this is hardly more than hypothesis. 

Philosophers of the past were accustomed to 
ascribe space to "outer perception,'* and time to 
"inner perception.*^ As these terms are now in- 
terpreted they meant sense perception and thought 



230 A SYSTEM OF PSYCHOLOGY 

(imagination, including memory), respectively, but 
this interpretation makes the distinction as regards 
space and time meaningless. We can imagine con- 
tent which involves spatial relations just as well as 
we can perceive it, and we can certainly perceive 
time. It is quite probable that these older phi- 
losophers had a more subtle meaning than their 
words adequately express to us; but it is not our 
task at present to search for this. 

The chief points of temporal content, upon which 
we shall touch lightly, are (1) passing time and 
change, (2) temporal extent, and (3) temporal dis- 
tinction and identification. 

(1) The immediate content, which is called "pass^ 
ing time, is change in the content of consciousness. 
We do not mean to say that time is built up out of 
change, but that change as directly perceived, in 
abstraction from any critical points in the series of 
changes, is the passing time. By critical points, 
we mean conditions of content from which the 
change is thought to occur, or toward which it is 
thought to be directed. Thus, if a sensation 
changes from one quality to another, the two quali- 
ties are critical points, and in so far as the change is 
perceived or thought of under the dominance of its 
relations to these — or their relations to it — it is not 
mere passing time. 



PERCEPTION 231 

Attend, in so far as you can, to the " time stream''; 
try to watch the "ceaseless avalanche of time'' itself 
instead of attending rather to the events caught in 
its rush, as you normally do, and you will find that 
the content which is thus emphasized is a restless 
"going, going, going"; a continual motion from 
nothing in particular to nothing else in particular; 
just continual change. This change may be in 
sensation, or in imagery, but as soon as it is defi- 
nitely located, as soon as the whence and the whither 
regain their normal emphasis, the passing time 
merges into concrete change. 

In transforming the world of immediate experi- 
ence into terms of substance and its attributes, we 
say that change requires Time in which it may 
occur; we postulate time as a sort of rack into 
which events are packed. Such Time, if it exists, 
is not the object of our direct perception, and al- 
though we may conceive of it we cannot imagine 
it. You may image time, but it is always as it is 
perceived, a concrete succession of changes; or 
rather it is something which readily becomes such 
a series under inspection.^ 

^ Time, with a capital T, is a metaphysical construct quite 
comparable to Space with a capital S. This is sometimes 
called ' physical ' time, but would better be designated * logical ' 
or ' mathematical' time. 



232 A SYSTEM OF PSYCHOLOGY 

A succession of changes presupposes seriality, 
i, e,, intermediacy. The change would be chaos if 
m2 were not perceived or imaged as between mi 
and m3. In other words, we intuit in the change a 
specific relation which we may designate as tem- 
poral betweenness, or intermediacy. This inter- 
mediacy, although it is not in the passing time as 
perceived, is an element in all other time-content. 

Rate of change is measured by the comparison of 
two series in content. If you notice a certain rate 
of change in auditory sensation, you are comparing 
it with the rate of change of such other sensory or 
imaginative content as is implicitly assumed as a 
standard. The perception of rate passes so readily 
into the perception of extent that we must at once 
consider that factor. 

(2) Temporal extent is the amount of change be- 
tween determining points. If you note in direct 
perception how long a sensation lasts, you are not- 
ing the beginning of the sensation and its end, 
which are two points of transition in the field of 
consciousness, between which, if we were restricted 
to the one sensation, and it were uniform — if it did 
not vary in any character from beginning to end — 
there would be no perceived time at all. But we 
are not restricted to this sensation, and we perceive 



PERCEPTION 233 

changes occurring in other sensations — increase or 
decrease in intensity, and so on — which in their re- 
lations to the determining points of the first sen- 
sation constitute the perceived time between those 
points.^ 

The duration or temporal extent may be made 
up of the total changes in the content; usually, 
however, a certain part of the content is selected, 
and change in other parts is not included in the 
total. The selected contents are normally the pe- 
riodic or rhythmic muscular activities: breathing, 
the heart-beat, or periodic movements of the limbs, 
as in walking; or even purposely produced pe- 
riodic contractions of other muscles, as tapping of 
the finger or slight movement in the throat. 

For practical purposes we find it convenient to 
use as standard extents of time the cycles of change 
of certain cosmic phenomena — the periodic pas- 
sage of the sun across the meridian; the stellar posi- 

^ The character of sensation which we have called duration, 
or protensity, is not to be confused with duration in the sense 
of temporal extent. The sensation would be perceived even 
if it were not perceived as having temporal extent; and two 
sensations having different physical durations would be per- 
ceived as differing in protensity even although no time were 
perceived as included in either. 

Protensity is the character of sensation by virtue of which 
it can have perceived duration, independently of any changes 
it may itself undergo. Duration proper is the protensity 
filled out by change in other sensation. 



234 A SYSTEM OF PSYCHOLOGY 

tions; and so on. Ordinarily, we employ as unit 
the day, that is, the interval between successive 
noons. Primitive man subdivided the day by the 
positions of the sun, corrected, doubtless, by the pe- 
riodic need and satiety of sleep. A little progress in 
astronomical observation showed the variation in 
solar days as compared with the sidereal, and the 
desire for harmonious subdivisions resulted in the 
partition of the day on a spatial basis, fifteen de- 
grees of longitude being the measure of an hour, 
fifteen minutes of longitude, one minute of time, 
and so on. These astronomical divisions of time 
are by no means equal for perception; one minute 
may be perceived as ten times as long as the next. 
The symbolical estimation of time is not restricted 
to the means of astronomical observations, pendu- 
lums, and such physical devices. Very often we 
measure intervals by the number of recurrences of 
physiological phenomena; as heart-beats, breaths, 
etc.; without regard to the actually perceived time- 
content. Before this trait was noticed certain 
phenomena of time-estimation were quite inexpli- 
cable; the fact that intervals corresponding to some 
multiple of the respiration-period were more accu- 
rately estimated than intervals falling between these 
in length was discovered some decades ago, and, 



PERCEPTION 235 

not being referred to the respiration at the time 
gave rise to much tenuous speculation. In other 
cases the breathing rhythm seems to be of less in- 
fluence and the heart-rate to dominate the estima- 
tions. 

In the direct estimation of time, any variation in 
the processes by which we estimate, or any change 
in the attention to them, affects the estimation. 
The apparent duration of a visual phenomenon 
occupying three physical seconds will not differ 
greatly, general conditions being the same, from 
the apparent duration of an auditory phenomenon 
of the same physical measure. In neither case is 
the time-content the change in the auditory or vis- 
ual content, but in some content— muscular, and 
perhaps ideational — which is the same in both 
cases; the beginning and the end of the estimated 
phenomenon simply mark off a certain amount of 
this change. The change in the estimated phe- 
nomenon is perceived simply as change, the rapid- 
ity thereof being determined by the amount of 
change in the other series — in the time — to which 
it corresponds. 

The apparent length of intervals marked off by 
tactual stimulations varies exceedingly from the 
apparent length of intervals marked off by visual 



236 A SYSTEM OF PSYCHOLOGY 

or auditory stimulation, especially in being more 
irregular. This peculiarity of tactually limited in- 
tervals is probably due to the fact that attention to 
tactual stimulation emphasizes also certain muscu- 
lar sensations from the member tactually stimulated, 
and this sensation merges in an irregular way with 
the more rhythmic muscular sensation constituting 
the basis of the time-content. 

The passing of time seems sometimes slow, some- 
times fast. This feature arises from the fact that 
we are comparing two series of changes whose rel- 
ative rates are variable. The measure of the time 
is the series of changes we may call St. The con- 
tent which is timed by that measure, the mass of 
sensation from the world about us, itself in constant 
change, we may call Sc. Now, while the rate of 
change of St is reasonably uniform — as compared 
with physical standards — the rate of change of Sc 
is highly irregular.^ If Sc is changing rapidly, as 
when a great many interesting events are happen- 
ing around you, time is perceived as flying. If, on 
the other hand, Sc goes slowly, as on days of 
deathly dulness, time is perceived as dragging. If 
all the changes in content not included in the time 

* Perhaps we should say merely that St is less irregular than 
Sc. 



PERCEPTION 237 

series should become insignificant, the experience 
would approximate to the perception of eternity; 
those who have been the subject of this in the de- 
lirium of fever doubtless remember the horror of it. 
In retrospect, the time that dragged may seem 
brief, as compared with an equal physical length of 
the time that flew. This seeming inversion of the 
duration relation is due to a peculiarity of our 
estimation of time intervals whose filling has once 
passed from consciousness. When you reproduce 
a series of past events, you time them by the present 
muscular series, just as if they constituted fresh 
content; for you could not, if you would, reproduce 
the past series of sensations forming the time basis. 
The richer series, now taking longer to run over in 
memory than does the poorer series, marks off more 
change in the time series, that is, it seems longer. 
On the other hand, the events of the past interval 
may not appear prominently; you may remember 
that they excited, interested, bored, or otherwise 
emotionally affected you, and this memory may serve 
as the symbol of the time length; the tedious ex- 
perience may be thought of now as tedious because 
the memory of the content recalls the aflFective or 
emotional experience connected with the slow pas- 
sage of the time. 



238 A SYSTEM OF PSYCHOLOGY 

(3) The relations of past to present and to future 
are so invariable and all pervading that they almost 
defy analysis. Practically all we can do here is 
to point them out; but that does not signify that 
the relations are simple. 

The present corresponds to the "here'' of space 
— the origin in a system of co-ordinates — and past 
and present correspond to " elsewhere." If we so 
desire, we can carry the analogy still farther in con- 
nection with the factors reality and unreality. We 
may imagine either past or future as real (memory 
and expectation), or as unreal. I may, for ex- 
ample, imagine myself as having made a successful 
balloon ascension yesterday, or as the proprietor 
of a restaurant to-morrow. We might therefore 
liken the past and the future to the positive and 
negative directions of a line, and the fictitious past 
and future to the ±|/"^. But the analogy breaks 
down, for the "reality" and "unreality" are not 
time factors, and we can imagine content as present 
and unreal, as well as present and real. 

"Reality" may be taken in another way, to sig- 
nify the intuited as against the imagined. This, 
again, is not a time factor, since content may be 
either intuited or imagined as present. It is only 
in a metaphysical way that I can identify the present 



PERCEPTION 239 

with reality, and past and future with unreality; 
for this identification is not a matter of immediate 
experience at all, but a symbolic way of stating the 
time relations. In so far as my immediate experi- 
ence is concerned, both past and future actually 
exist.^ 

The temporal factors of pastness and futurity 
have essentially connected with them the factors of 
familiarity and novelty. What is apprehended as 
past is also recognized, that is, it has the element of 
familiarity; but we cannot say that pastness and 
familiarity are one and the same thing. Familiar- 
ity, it is clear, may attach to a content which has 
novelty; something may be both future and famil- 
iar. It is quite possible that these factors are ulti- 

^ There are many interesting problems in the metaphysical 
view of time. If the past does not exist, any account of it is 
pure fiction, and history and mythology are alike only at- 
tempts to systematize a present content, true in so far as they 
succeed; historical truth depending therefore merely on the 
extent and quality of our present information. To say that 
the past does not exist, but did exist is a mere quibble, just as 
it is to say that to-morrow will he Monday. If the past is, 
then the events of the past were; if to-morrow is, then the 
events thereto pertaining will he. To say that to-morrow will 
be, or that the past was, is either a misstatement or a meta- 
phor. 

Whatever the " reality '^ factor of content may be, analysis 
so far has simply indicated it. It is doubtless a relation or 
group of relations — a ^'feeling of realty," the current empirical 
philosophy would call it — and there we are obliged to leave 
it for the present. 



240 A SYSTEM OF PSYCHOLOGY 

mate elements, and we may accept them as such 
provisionally. 

The present moment of perceived time may be 
said to be a mere position in which all content has 
its origin, and from which it ceaselessly flows. This 
present moment, in other words, does not include 
any duration. In this respect it is like the present 
moment of logical ('^physicar*) time, which must be 
represented as a mere point on a line. The actual 
present, however, cannot be represented by the 
logical present; that is to say, that when the actual 
present moment is schematized in such a way as to 
show the various features of content and of proc- 
esses connected with it, in logical time relations, 
this present is represented not by a point, but by an 
appreciable extent of " physical^' time. 

Another way of describing the relation between 
the actual present and the logical present is to say 
that the content may include factors which ap- 
pear simultaneous, but whose physical causes (and 
probably whose physiological processes) are sepa- 
rated by some interval in the physical series. For 
example: a hand revolving over a dial may pass 
the zero mark a fraction of a second before or after 
a bell stroke occurs, and yet the two occurrences 
may seem simultaneous. The perception of the 



PERCEPTION 241 

pointer at a definite place on the dial necessitates 
an eye movement, which, in some way not entirely 
understood at present, allows an ^'instantaneous 
photograph'" on the retina of the pointer at the given 
place; without this eye-movement the image blurs. 
When the click appears immediately before or after 
the eye movement no time is perceived as inter- 
vening, that is, the visual impression and the audi- 
tory impression are judged to be simultaneous. 



CHAPTER XIV 

AFFECTIVE CONTENT OR FEELING 
I. Affection and Cognition 

Perception and imagination are classed as cog- 
nition, and sensation and relations, therefore, as cog- 
nitive elements. These factors do not exhaust the 
sum of content, or at least there are sorts of con- 
tent which have not been demonstrated as reduc- 
ible to sensation and relation. 

When I experience an object, I may experience 
it qualified by pleasantness or the opposite. A cer- 
tain amount of what for want of a better term we 
may call interest may also attach to the object. If 
I imagine a content it may be tinged with desire or 
repugnance. These factors — pleasure, pain, de- 
sire, repugnance, and interest — constitute the affec- 
tive tone of the content in so far as they are present. 
They are sometimes looked upon not as factors in 
the content, but, (1) as ways of experiencing it, or 
(2) as attitudes toward it, or (3) modes in which the 
ego is affected in experiencing it. These three ex- 
pressions, which are practically equivalent, mean 

242 



AFFECTIVE CONTENT OR FEELING 243 

nothing more than that the content of experience 
is not completely accounted for in analysis in terms 
of cognitive factors only; that the non-cognitive 
or affective factors are as truly sui generis as are 
the cognitive factors. 

Affective content includes not only the elements 
(or quasi-elements) just mentioned, but also the 
more complex factors called emotions and emotional 
tone. For example, the content may be joyful, 
pathetic, humorous, or revolting. 

Pleasure, pain, interest, desire, and repugnance, 
may be designated as feelings, or, abstractly, as 
feeling. Pleasure and pain are designated as 
hedonic tone or algo-hedonic tone; the experience of 
pleasure and pain, considered generally, is hedono- 
algesis.^ Desire and aversion are designated ad- 
jectively as conative or appetitive, and the experience 
of them as conation or appetition, 

^ The term "feeling tone'' is commonly given to pleasure- 
pain alone: frequently the two qualities are designated as 
pleasantness and unpleasantness. Some psychologists apply 
the term "feeling tone" also to certain obviously sensory 
elements or factors, especially strain and relaxation. 

" Feeling" has been much used in the past in the sense of 
emotion, but is not so used at present in strict discourse. 

Often, however, the term is extended to cover what we 
have designated as relational content; thus, a "feeling of 
similarity" is not an uncommon expression. In loose speak- 
ing, "feeling" is used to designate any sort of content what- 
ever. 



244 A SYSTEM OF PSYCHOLOGY 

The most conspicuous feature of feeling and 
emotion is the pairing off of the different qualities 
and qualitative complexes in antithetical fashion. 
The two conative qualities are mutually opposed to 
each other, as are also the algo-hedonic qualities, 
and for almost every emotion there is an opposite. 
This raises the suspicion that all the emotions are 
based on the feelings, and that very probably there 
are more feelings than the ones we have named. 

2. Pleasure and Pain 

Hedonic tone attaches not only to sensational 
experiences but also to content of all kinds. An 
idea is pleasant or unpleasant; the memory of your 
misfortune yesterday involves painful elements, the 
idea of the good time to-morrow brings pleasure 
with it. The recognition of relations, whether in 
idea or immediate perception, rouses hedonic or 
algetic factors, and sometimes vividly; even the 
solution of a problem in Euclid brings pleasure. 
Emotional states can be classified on the basis of 
their hedonic tone. 

In some respects hedonic tone resembles sensa- 
tion. It has the characters of quality, intensity, and 
duration. Other forms of content (relations, pos- 
sibly images,) can hardly be said to possess inten- 



AFFECTIVE CONTENT OR FEELING 



245 



sity. Affective elements have no specific physical 
stimuli : in this respect they resemble visceral sensa- 
tions. But on the other hand, the feelings cannot 
be identified with any peripheral nervous mechan- 
ism or process; in which they are analogous to rela- 
tions. 

The quality and intensity of hedonic tone ac- 
companying sensations are determined by the sen- 




UNPL 



Fig. 12. 

The curves in fig. 12 represent schematically the relation between 
feeling and sensation intensity. The abscissa represents the intensity 
of the sensation, and the plus and minus ordinates represent the corre- 
sponding degrees of pleasantness and unpleasantness respectively. 



sations in fairly simple ways. The intensity, dura- 
tion, and the number of repetitions of the sensation 
seem to be the important factors. If the sensation 
is of brief duration, it is usually pleasant at low 
intensities, the degree of pleasure depending on the 
sensation-quality, and on the individual and his 
condition. To most of us, a faint smell of lilac is 



246 A SYSTEM OF PSYCHOLOGY 

agreeable, but as the intensity of the odor increases 
the pleasure decreases, changing for some persons 
to unpleasantness with high intensity of the sensa- 
tion. (See Curve II of Fig. 12.) For other per- 
sons the odor may remain pleasant at relatively high 
intensities. (Curve I.) For the most part, sen- 
sations are slightly pleasant when suflSciently faint, 
(Curve III), although some are indeed merely 
neutral, and some are unpleasant for some persons 
if above the threshold at all. (Curve IV.) 

The duration of the sensation exercises an influ- 
ence on hedonic tone; or, rather, the tone varies ac- 
cording to the duration of the sensation. A flash 
of color, a brief skin-tickle, a whiff of musk, may 
be agreeable, although a longer continuation makes 
the sensation intolerable. In the cases of some sen- 
sations, the feeling may not be changed to the oppo- 
site, but simply become less pleasant or more un- 
pleasant; but the effect of a longer duration of the 
sensation is always to send the tone in the unpleasant 
direction. At the same time, it must be remem- 
bered, the continuance of a stimulation produces 
progressively less response from the sense-organ, 
and hence less intensity of sensation. 

Repetition may make a sensation which is orig- 
inally unpleasant less so, or even pleasant. Bitter 



AFFECTIVE CONTENT OR FEELING 247 

becomes a pleasant taste, and discord a pleasant 
sound, with habituation thereto. Possibly all food 
flavors are unpleasant to the child experiencing 
them for the first time; the instinct to eat and the 
desire to do what others do impel him to continue 
to ingest the food and drink offered to him, and he 
quickly learns to like them. Where a sensation be- 
comes more unpleasant with repetition, the organ 
has undergone a change — pathological, perhaps — 
such that the stimulus really produces a more in- 
tense sensation, as in the case of a tooth which the 
dentist has been torturing intermittently; or ideal 
factors have entered, with their effects on feeling, 
as when one revolts from a formerly toothsome 
dish after seeing the details of its preparation. 

In the realm of ideas and relations the conditions 
governing pleasure and pain are highly complicated. 
That we can remember or imagine affective ele- 
ments is denied by some psychologists. Perhaps 
individuals differ in their power of imagining such 
contents. On the other hand, the idea or image of 
past or future experience may arouse actual pleasure 
or pain at the moment of the experience of the 
idea, and so the belief in reproduced hedonic tone 
may be due to the mistaking of the tone of the 
image for the image of the tone. The idea of past 



248 A SYSTEM OF PSYCHOLOGY 

events is not always pleasant if the past content was 
pleasant, nor unpleasant if the past content was 
unpleasant. The determining causes of hedono- 
algetic quality seem to lie deep, and to operate in 
sense perception as well as in ideation; the quasi- 
principles above laid down in regard to sensation 
being, perhaps, specific results of these general 
causes. 

In the first place, the normal physiological activi- 
ties, those which go on as they should for the wel- 
fare of the individual and the perpetuation of the 
species, give pleasure; any interference with the 
usual course, or anything detrimental to the organ- 
ism, gives pain.* 

In the second place, whatever simulates some 
condition which is organically advantageous, gives 
pleasure. Drugs which produce effects on the ner- 
vous system temporarily like the effects of rest or 



^ This connection of algo-hedonic tone with the normal may 
be supposed to be the result of natural selection. Animals 
which failed to get pain from mutilation, exhaustion, or hun- 
ger, and pleasure from food and the society of the opposite 
sex, would have less chance for individual and racial survival 
than those which were "normal" in that regard. We should 
expect to find certain capacities for pleasure, e. g., of intoxica- 
tion, which are in themselves harmful, that have not been 
eliminated because of their connection with other and bene- 
ficial activities, or because natural selection has had no chance 
at them. 



AFFECTIVE CONTENT OR FEELING 249 

normal activity produce also the pleasurable ac- 
companiments of these conditions. 

In the third place, the carrying out or comple- 
tion of any activity; the accomplishment of any 
purpose; or the contemplation of a purpose ac- 
complished, give pleasure. The hindering or ob- 
structing of activity; the failure to carry out a pur- 
pose; the contemplation of a plan obstructed or 
an accomplishment obliterated; any of these give 
pain. Solving a problem, carrying out schemes of 
politics or business, playing a game successfully, 
contemplating your rise from barefoot boy to 
banker — these are instances of the one sort. Get- 
ting "stuck'' in a problem, failing to get command 
of a game, recalling your recent wealth or influ- 
ence, are instances of the other. 

The general rule, in short, is that the normal and 
successful performance of functions, physiological 
or mental, is accompanied by pleasure, and the 
fact that certain exceptions occur is evidence merely 
that the physio-psychological mechanism is not per- 
fectly adapted for all contingencies. 

As soon as we recognize pleasure and pain as 
primarily the concomitants of the organic welfare 
of the individual, we are led to suspect that they 
are forms of visceral sensation. AVe might reason- 



250 A SYSTEM OF PSYCHOLOGY 

ably suppose that the well-being of the vital organs, 
and the proper discharge of their functions, cause 
the stimulation of appropriate nerve endings, and 
as a result, somewhere in brain or in spinal cord, 
takes place the neural process specifically corre- 
sponding to pleasure. So too, the vital organs in 
unfavorable circumstances might arouse sensations 
of pain. Nervous excitations through the organs 
of "external" sense, or the neural correlate of idea- 
tional activity, being intimately connected with the 
condition of the organism, have possibly acquired 
either the power to excite the visceral organs by re- 
flex nervous discharges, or else the power to excite 
directly the neural centre of hedono-algetic feeling. 
This sensational theory of pleasure and pain is 
to be regarded merely as a live hypothesis. It is 
not at present any more probable than the oppo- 
site hypothesis; viz,, that pleasure and pain are 
content of a kind different from sensation. 

3. Conation and Interest 

Desire and repugnance are antithetical, as are 

pleasure and pain, and are usually so connected 

with the lat'ter functionally that what is pleasant is 

desired, and what is unpleasant is repugned/ 

* We use here the verb ''repugn " as the exact opposite of the 
verb '' desire". This usage is rare in English hterature, but 



AFFECTIVE CONTENT OR FEELING 251 

Conative factors attach only to imaged, ideated, 
and conceived content. If an object is present to 
sense — intuited — it is pleasing or displeasing, but 
cannot be desired or repugnant. When an object 
is perceived, some further content connected with 
it may be conatively colored. Thus, when fruit is 
before my gaze, I cannot desire the sight of it, for 
that I already have; but I may desire the taste, or 
a continuance of the sight, or the complex relations 
known as ownership. So the nasty medicine forced 
on the child is not repugnant as he experiences it, 
but the taste and effects imagined as a future pos- 
sibility are decidedly repugnant. 

Interest is verbally the opposite of apathy, but 
the two factors are not antithetical, as are desire 
and repugnance. Apathy is really the zero-point 
of interest, corresponding to the neither-pleasant- 
nor-painful; the neither-desired-nor-repugnant. 
There is only one quality of interest. A high de- 
gree of interest may coincide with either the pleas- 
ant or the painful, the desired or the repugnant. 

it is necessary to make this addition to psychological termin- 
ology because we have no other word which can serve as a 
precise term for the opposite of ''desire/^ *' Aversion'' is fre- 
quently used for the noun, but is not unambiguous, and has no 
verb form. We might even venture a step beyond precedent 
and use the noun "repugn" as the opposite to the noun "de- 
sire." 



252 A SYSTEM OF PSYCHOLOGY 

The glorious sunset; the vile chemical laboratory 
smell; the recollected images of yesterday's good 
fortune; the idea of to-morrow's catastrophe; all 
may be permeated by intense interest. 

Interest attaching to one feature of a complex 
content spreads over the other factors of the con- 
tent. The firmer the association between the in- 
trinsically interesting factor and the other factors, 
the more these share in its interest. Pedagogues 
universally recognize this fact, and, therefore, in pre- 
senting any subject to children, they inject anec- 
dotes, bring out details which are not essential to 
the subject-matter, but which are interesting to the 
child,^ and in every other way possible mingle with 
the dry material interesting stuff which can be as- 

^ It is customary to say "appeal to the child's interest/' in- 
stead of ''possess interest for the child." This form of ex- 
pression indicates the survival of the view of content of vari- 
ous sorts as products of the ''faculties" of the individual. 
Under the "faculty" theory the various terms designating 
different divisions of the field were applied indiscriminately to 
the content and to the hypothetical "faculty" producing the 
content. This " faculty psychology" is by no means dead at 
present, and has the greatest vitality in the realm of the feel- 
ings. The student must be careful not to allow the common 
ways of speaking of psychological facts to draw him into a 
false understanding of them. You may say "I admire St. 
Gaudens' statues" and " I became interested in polar explora- 
tion," but don't forget that admiration and interest, to what- 
ever activities they may lead, are factors in the content of 
your consciousness, and not anything supplied by your con- 
sciousness or your ego. 



AFFECTIVE CONTENT OR FEELING 253 

sociated with it. Contemporaneous events; de- 
tails concerning the person, country, or organiza- 
tion under consideration, and especially causes 
and effects, form associative nexus over which the 
interest readily travels. But even such artificial 
associations as may be formed between | and the 
red apples used to illustrate the problem, may 
carry interest from the fruit to the arithmetic, 
for the good of the child and the success of the 
teacher. 

Desire and repugnance spread, but not simply 
along the lines of association. In certain cases the 
invariable associates of desired or repugnant things 
become invested w^ith the given feeling, sometimes 
to the exclusion of that which it originally attached; 
but these cases — fetichism, so called — are excep- 
tional. In general, the organic whole which is 
ideated — for example, a trip to Europe — is desired 
(or the reverse) in so far as one or more important 
factors in the idea have the feeling, but the cona- 
tive feeling does not tend to flow over and color the 
other cognitive factors, or at least not to the same 
extent as does interest. However ardently you 
desire the European trip, the sea voyage essential 
thereto may remain repugnant, and certain details 
of continental travel remain conatively neutral. 



254 A SYSTEM OF PSYCHOLOGY 

But your interest in the means and conditions of 
travel swells almost in proportion to your interest 
in foreign lands. 

In the particular instance cited, the abhorred 
factor — the ocean trip — becomes desired, in spite 
of its unpleasantness, as soon as you begin to make 
definite plans for beginning your vacation. You 
contemplate the voyage as a necessary link in the 
chain of causation which will bring the intrinsic- 
ally desired details of the stay on the other side. 
Conative feeling, in other words, spreads along the 
line of causal relation in the regressive direction. If 
you desire anything, you will desire the causes 
thereof, unless those causes are so tinctured with 
repugnance that the desire of the effects cannot 
overcome it. There are persons who are such 
"poor sailors" that not all the joys of the other 
continents can overcome their aversion to the un- 
easy ocean. 

Conative feeling never spreads progressively along 
the line of causation. You may be averse to the 
sea voyage because of the repugnant consequences; 
but no matter how much you desire to take ship, 
the consequent mal de mer will never become in the 
least desired. However fierce may be your long- 
ing for any pleasurable content, it will not add one 



AFFECTIVE CONTENT OR FEELING 255 

jot to your desire for the consequences, nor sub- 
tract one tittle from your repugn for them. 

The desire or repugnance attaching to a cause — 
or what is conceived as a cause — does have an in- 
fluence on the interest attaching to the effect. If 
the effect has the opposite conative feeling, it is de- 
creased in interest, sometimes even to the apathetic 
point. The dipsomaniac, eager for the pleasant 
excitement of intoxication, does not desire the next 
day's wretchedness; but that result he refuses to 
ideate — it has no interest for him while his desire for 
intoxication lasts, and interest, as we shall see, 
is one of the important conditions of attention. In 
this curious relation of interest to antagonistic cona- 
tive feeling is doubtless to be found a clew to the 
further understanding of interest. 

4. Emotion 

Emotion includes in the first place the affective 
elements just mentioned, and perhaps other such 
elements. In the second place, it includes among 
its factors bodily sensation, and in the third place 
intellectual factors. Sensory imaginative content 
is included in many instances. 

The affective elements are combined in an organ- 
ized content in normal consciousness in the manner 



256 A SYSTEM OF PSYCHOLOGY 

we have indicated in the preceding section; either 
hedonic tone, or either conative factor may appear 
with any degree of interest: if both hedonic tone 
and conative factors are present, (as in ideation), 
repugnance goes with pain and desire with pleasure. 
In morbid imagination the conditions may be re- 
versed; pleasure may be coupled with repugnance 
and pain with desire. 

A few examples of affective combination in emo- 
tion will illustrate the possible exclusions of one or 
another of the three feeling groups. Grief or joy 
may be entirely devoid of desire and aversion. 
Grief may lose interest until it sinks approximately 
to apathy. Ennui is painful, rather apathetic, and 
repugnant in so far as its continuance is ideated. 
On the other hand, the idea of the removal of its 
cause is pleasant and desired. Hate may be de- 
void of hedonic tone, and full either of desire or 
repugnance, according as the object of the hate is 
thought of as suflFering or prospering. 

Examples of morbid emotion are found in cases of 
asceticism where the "pleasures of the flesh" are 
thought of with aversion, and various sorts of pain 
are desired. The ideal of the monkish life is to rid 
the ideas of things, commonly desired or repugnant, 
of their normal pleasure or pain: in so far as this 



AFFECTIVE CONTENT OR FEELING 257 

ideal is realized the emotions are not morbid; they 
are abnormal only in the sense of being unusual. 
It is possible that in some diseased mental conditions 
(other than the quasi-ascetic) the patient may desire 
what is thought of as painful, and be averse to what 
is thought of as pleasant. 

In cestlietic emotion desire and repugnance are ex- 
cluded. My present emotion with regard to the 
Fifth Symphony of Beethoven is not aesthetic; it is 
a commonplace affair in which the desire to hear the 
symphony predominates : the emotion while listening 
to the symphony is sesthetic if no desires are mingled 
in it. The painting of a mere basket of fruit can 
hardly arouse aesthetic emotion, because the desire 
to taste the fruit is excited if the painting is skilfully 
done (there are exceptions, however), and the repre- 
sentation of a beautiful woman is decidedly un- 
sesthetic if it arouses sensuous desire. So, too, in so 
far as anything arouses repugnance, it is an unaes- 
thetic object.^ 

The ideals of art are not satisfied by the mere 
arousal of aesthetic emotion. Art aims to carry us to 

* The ideal religious emotion is complementary to aesthetic 
emotion, in that desire and repugn are included, and pleasure 
and pain excluded. The common type of religious emotion, 
or what passes for such, is generally tinctured heavily with 
hedono-algetic factors. 



258 A SYSTEM OF PSYCHOLOGY 

the point where the sensuous and intellectual con- 
tent is minimized, and the feeling element is para- 
mount. This aim can be attained measurably by 
painting and sculpture, but more adequately by 
poetry and music. In poetry, the ideas called up 
by the words are necessarily definite and in so far 
obtrusive, but the skill of the poet is exerted to 
subordinate this machinery to the results achieved 
by its aid. This is the reason why description, 
narration, or philosophizing, essentially interfere 
with the poetic effect, although they may produce 
a pleasing result; and the poet accordingly employs 
them only in so far as the ideas they arouse are 
fragmentary and therefore subordinate to their 
feeling. 

In music, we are less trammelled by the cognitive. 
The mere sounds are not of high interest in the 
total complex, and they do not in general arouse 
definite ideas. There are exceptions, in what is 
known as "programme-music,'^ in which certain pas- 
sages are supposed to suggest the singing of birds 
in the woods, etc., and although some musicians 
condemn this intrusion of ideas, it may be helpful 
in some cases. The mingling of music with sensu- 
ous and intellectual content in opera, while a lower 
form of art for those able to appreciate pure music, 



AFFECTIVE CONTENT OR FEELING 259 

may be a means by which more powerful feeling 
is roused in certain persons than they would other- 
wise experience. The purity of the feelings is one 
ideal, and the strength of feeling and richness of 
content is another, between which the choice is a 
matter of personal response. 

5. The Coenaesthetic Factor in Emotion 

The discovery that emotion contains much vague 
and undiscriminated bodily sensation was made 
about thirty years ago, simultaneously, by James of 
Harvard and Lange of Copenhagen. Prior to that 
time the opinion prevailed that the bodily factors we 
experience when emotionally moved are conse- 
quences of the emotion proper— the theory of Des- 
cartes. Spinoza had stated the doctrine of the 
bodily factors as an integral part of the emotion, but 
in a crabbed and symbolic way which produced but 
slight effect on psychology. Lange and James 
went so far as to claim that the emotion consists 
wholly of bodily sensation — the so-called James- 
Lange theory — and although we are not inclined to 
grant this claim it is not because we are essentially 
at variance with the James-Lange view, but because 
they mean by emotion only what is left over after 
the intellectual and ideo-cognitive factors are ex- 



260 A SYSTEM OF PSYCHOLOGY 

eluded, and possibly after the exclusion of what we 
have designated as the true affective factors, while 
we prefer to use the term in the wider sense in 
which the public understands it/ 

The trembling of the limbs, the modified beat 
of the heart, the peculiar visceral states, and, per- 
haps, the results of certain glandular activities, are 
certainly a large factor in fear, and if they are ab- 
stracted the characteristic emotion is dispelled. 
So in the case of pathos; the emotion derives its 
specific character from certain sensations connected 
with swallowing and relaxation, characteristic of 
satisfaction, and with the retching movements 
characteristic of disapproval or disgust; for the 
essential thing in pathos is a mingling of these two 
emotional complexes. Other illustrations of the 
coensesthetic factor in emotion may readily be found. 

The mass of sensation in emotion is undiscrimi- 
nated and vague. When you pick out this factor 
and identify it with the respiration, and identify that 
factor with the leg muscles, and the other factor with 
the intestinal condition, the emotion is thereby de- 
stroyed. It is only so long as these sensations fuse 

^ For a statement of Professor James's theory, and the multi- 
tude of facts which suppoix it, read the chapters on '' Instinct 
and Emotion '' (XXIV and XXV), in vol. II, of his Principles 
of Psychology. 



AFFECTIVE CONTENT OR FEELING 261 

into an undifferentiated mass that they are a ^* color'* 
or "background" for the cognitive content; when 
discriminated they are cognitive content themselves, 
losing their quasi-unique character. Moreover, 
the visceral sensations are always vague, and 
identification of them is difficult, even when one 
makes great effort to analyze. 

It is possible that in many cases the actual sensa- 
tions are replaced by images thereof; so that a man 
whose heart and diaphragm no longer respond to 
the stimulation of a threatening circumstance still 
may feel fear through the recall of the appropriate 
sensations in imagination. This supposition would 
be contrary to the seeming fact that bodily sensations 
are in general not imagined, but, nevertheless, it is 
not yet excluded. 

6. The Cognitive Factor in Emotion 

An emotion is always built up on some cognitive 
content, and loses its distinctive character when con- 
sidered apart from that factor. The reference of 
the emotional complex to the "object'' of the emo- 
tion furnishes the basis of its specific organization. 
Emotional content not attached to a specific cogni- 
tive content — which has no^ a specific "object" — 
is not dignified with the name of an emotion, but 



262 A SYSTEM OF PSYCHOLOGY 

is called an emotional mood. Joy and sorrow, di- 
vested of the definite reference to the object or event 
which they envelop, become mere elation or depres- 
sion. Hate which is not the hate of some one or 
thing is a mere savage mood. These moods are 
common, and may be produced by strictly physio- 
logical causes; melancholy, the mood correspond- 
ing to grief, is notoriously a result of disordered 
bodily functions. On the other hand, an emotion 
may resolve itself into a mood which persists long 
after the transition. 

In addition to the general reference of an emo- 
tion to its "object,'' there are explicit relationships 
or groups of relationships involved in emotions. 
These relations appertain primarily to the "object," 
but are essential to the emotion. Thus, reverence 
and contempt involve the perception or conception 
of the object as superior or inferior in some respect; 
usually a relation of the sort we designate as per- 
sonal. Fear involves the consciousness of the ob- 
ject as threatening us; hope, as possibly attainable. 
Despair permeates the object which is ideated as 
forever sundered from our possession. Love has 
been defined as pleasure plus the idea (or percep- 
tion) of the object producing the pleasure; this 
half-truth brings out clearly the fact to which we 



AFFECTIVE CONTENT OR FEELING 263 

refer. Mere pleasure, with the perception of the 
pleasing object, is " taking pleasure in the object," 
and nothing more; but given the proper relation 
in which the object is conceived as standing to 
other things, the emotion may become one of warm 
approval; and, given certain relations in which the 
object is conceived to stand to yourself, the emo- 
tion may become love. 

From the above considerations it ought to be 
evident that any analysis of the emotions which 
attempts to reduce them to sensations alone, or to 
sensations and affective elements, is inadequate. 

7. The Classification of the Emotions 

Many attempts have been made in the past to 
enumerate the principal or distinctive emotions, or 
to tabulate the main classes into which all emotions 
should fall. Success has crowned none of these 
efforts; they have not even gained ground from 
which further advance may be made. 

The varieties of emotion are actually indefinite, 
and practically infinite in number. One emotion 
shades off into another by slight gradations, and 
definite delimitation is entirely out of the question. 

We might, indeed, make rough divisions of emo- 
tions on the basis of hedono-algesis, setting those 



264 A SYSTEM OF PSYCHOLOGY 

which contain painful factors over against those 
which contain pleasant. Or we might classify on 
the basis of desire and aversion. A distinction has 
been made also between the egoistic or self-re- 
garding, and the altruistic emotions. Many other 
principles of classification might be suggested, but 
they are for the most part applicable to a few cases 
only, and they are all practically useless. 



CHAPTER XV 

ACTION AND WILL 
I. Action in General 

The actions of which the human body is ca- 
pable may be divided usefully into two classes: 
physiological reflexes and consciousness-reflexes. 
The first class, which includes the actions in which 
consciousness plays no essential part, is but in- 
directly of interest to the psychologist, although of 
extreme importance in vital function. The physi- 
ological reflex may be produced artificially by di- 
rect excitation of the muscles by mechanical, elec- 
trical, or chemical stimuli; by electrical stimulation 
of the efferent (motor) nerves; by stimulation of 
the motor cells of the cortex or in the lower cen- 
tres; and perhaps by electrical stimulation of cer- 
tain sensory nerves. The exact method of pro- 
duction of the natural physiological reflexes — such 
as breathing, heart-beat and arterial dilation and 
contraction, intestinal peristalsis, glandular secre- 
tion, pupillary reflex — need not be discussed in de- 
tail here. In the case of the pupillary reflex and 

265 



266 A SYSTEM OF PSYCHOLOGY 

the heart-beat, the activity of the muscle probably 
is determined largely by local stimulation. In the 
case of breathing, the movements are wholly ini- 
tiated by nerve-currents from centres in the cere- 
bellum. The movements of swallowing are prob- 
ably brought about through tactual sensations 
(from the mouth) which excite certain nerve-centres, 
which in turn excite the muscles of the mouth and 
gullet. This last process is usually in part a con- 
sciousness-reflex. 

Actions of the second class are those in which 
consciousness plays an important role, and of these 
four types may be distinguished: sensational re- 
flexes, or sensory-motor processes; perceptual re- 
flexes; ideational reflexes, or ideo-motor processes; 
and voluntary actions, or volitional processes. 

In the sensational reflex the consciousness nec- 
essarily involved is a sensation merely. Thus, the 
hand is mechanically retracted upon coming into 
contact with a hot object; the mere apprehension 
of heat is sufficient to bring about the reaction, and 
the apprehension of a definite hot object is not nec- 
essary, although it may be important for further 
action. Winking when a cinder gets in the eye, is 
another typical sensational reflex. It is possible 
that some of the instinctive actions of the young 



ACTION AND WILL 267 

animal may belong to this class. The first suck- 
ing movement of the babe, for example, may be 
conditioned by the mere tactual sensations aroused 
by the nipple on its lips. On the other hand, these 
actions may be mere physiological reflexes, or they 
may, for aught we know, depend on definite per- 
ceptions. 

The perceptual reflex, depending on apprehen- 
sion of content more complicated than mere sensa- 
tion, is in adult life more important than the mere 
sensational reflex. The almost unavoidable wink- 
ing when some object comes quickly toward the 
eye; the instinctive putting up of the hand to ward 
off or catch an object; the flow of saliva at the 
smell of savory food; the unintentional mimicking 
of an acrobat by an interested spectator: these are 
typical perceptual reflexes. 

The consciousness immediately antecedent to an 
action may not be of presented content at all, but 
may be purely ideational. Action under such con- 
ditions we designate as ideational reflex. There 
are many cases in which the mere thought of an 
act brings the act about. Think of blinking; of 
inhaling deeply; of looking behind you; of yawn- 
ing; and the act will occur. Thinking of the re- 
sult of the act may be sufficient to produce it; in 



268 A SYSTEM OF PSYCHOLOGY 

many cases, thinking of a word is accompanied by 
the speaking of the word. It is probably true that 
every act thought of, either by imaging the act or 
by imaging the result thereof, would immediately 
" realize itself if there were not other factors which 
interfere, as there are in most cases. In hypnosis 
it is probable that these inhibitory factors are sup- 
pressed, and hence the ideas communicated to the 
patient have a chance to work themselves out rather 
freely. If you arouse in the patient's consciousness 
the idea of a horse, contradictory ideas being in 
abeyance, he will produce (as nearly as his bodily 
capacity permits), the acts characteristic of a 
horse. 

Certain ideas are linked with certain muscular 
and glandular activities, although they are not the 
"ideas of" the activities, nor "ideas oV the re- 
sults. The rather complicated ideational content 
involved in the notion of shame, for example, 
causes relaxation of the blood-vessels in such a way 
as to give rise to a blush. The idea that some one 
has treated you with indignity causes the changes 
which are felt in anger. An individual's idea of 
his superiority to other people may cause him to 
laugh or to smile. The list of illustrations might 
be extended indefinitely. 



ACTION AND WILL' 269 

If the ideational or perceptual reflex is compli- 
cated, i, e., if there are a number of details of action 
which must occur — some simultaneously and some 
in succession, — in order to produce a definite effect, 
as in walking or in catching a ball, but if, never- 
theless, the group of activities is as a whole depend- 
ent on the ideational or perceptual fact, as in the 
instances mentioned, the combined actions are 
called an automatic action. If an automatic action 
or a complicated physiological reflex occurs with- 
out its having been learned, it is said to be instinc- 
tive. If a nestling of a certain age is thrown into the 
air, it will fly; this first flying of the young bird is 
an instinctive action. 

Voluntary action is an ideo-motor process, but 
it includes more than the mere ideational reflex. 
The specific differentia of the voluntary action is 
desire (or the opposite). If I merely think of 
grasping the ink-well which stands on the desk be- 
fore me, I probably shall not act on the idea. But 
if I desire to grasp the ink-well, I shall grasp it, 
unless very influential counter-ideas are in my con- 
sciousness. 



270 A SYSTEM OF PSYCHOLOGY 

2. Volition 

We have indicated above that volition is an emo- 
tional state which involves as its essential features an 
idea of a future condition (anticipatory idea) with 
desire of (or repugnance to) that condition. Not 
every emotion of desire (or of repugnance) is, how- 
ever, a volition. A volition is an emotion of desire^ — 
what we commonly call the "desire of something 
— in the absence of any influential contrary idea 
and conation. If you see some choice fruit on a 
tree and are devising means by which you may 
obtain possession thereof, it is immaterial whether 
we say you desire the fruit, or that you will to get it. 
But if you entertain the idea that the taking of the 
fruit would be wrong, or suspect that the owner 
is near; and are averse to the act or its conse- 
quences under these conditions; and if the aversion 
is strong enough to prevent the plucking of the de- 
sired fruit; we should call your content desire, and 
not volition. 

The total content of consciousness, where it is 
marked by opposing ideas and conation, is called 



^ We shall speak only of desire, but with the understanding 
that the same remarks apply also, mutatis mutandis, to cases 
in which the conative factor is repugnance. 



ACTION AND WILL 271 

deliberation. Put in active terms, you deliberate 
over (literally, weigh) the desirable and undesirable 
possibilities in the way of results of the action. One 
of the ideas may shortly gain the ascendancy; the 
other either fading out of consciousness or losing 
its conative strength, and thus the content become 
a volition. This resolution of opposition or sub- 
ordination of inhibitory content, by which the mind 
"pulled several ways" becomes "confirmed in one 
direction'^ is called decision or consent. Some- 
times it is called the fiat. 

We are prone to think of deliberation as the hesi- 
tation of the self between alternative lines of possi- 
ble activity, and of decision as the active choice 
by the self of the one or the other. The part played 
by the self in deliberation and decision may be 
made more intelligible later, but for the present 
it is suflScient to say that the most adequate 
conception of these states is as mere matters of 
content; there is no discoverable force — as of 
an Ego or active self — at work transforming the 
content. 

It is not necessary that deliberation or decision 
should precede or form a part of volition. The 
anticipatory idea may be offset by no ideas of op- 
posing acts or of restraints, and yet the act which 



272 A SYSTEM OF PSYCHOLOGY 

succeeds may be strictly voluntary. The boy who 
sees the apple, anticipates with desire the ingestion 
thereof, and takes possession of it without a thought 
of owner^s rights or owner's wrath, performs an 
action as truly voluntary as if he deliberated over 
the situation for some time, and came to a decision 
with an experience of great effort. The line be- 
tween volition and desire (emotion) is manifestly 
not sharp, nor is there any great need of making any 
sharp distinction, either in ethics or in psychology. 
The distinction between voluntary action and ideo- 
motor process is clear for the extreme cases, but the 
two run into each other in a middle ground, where 
discrimination is impossible. 

The desire of a given effect is called the motive 
of the desire of its cause, or the motive of the volition 
based on the latter desire. The boy's desire or will 
to project the stone through the window may be 
motived by a desire to annoy the occupants of the 
house. The term motive is applied also to certain 
other antecedents of an act; the boy's motive for the 
window-breaking may be said to be the hatred with 
which he regards the householder. The motiving 
emotion has always desire or repugnance as a con- 
stituent; it is because the boy's hatred for the man 
includes as its prominent factor a desire to see him 



ACTION AND WILL 273 

degraded in some way, that it can be considered a 
motive. A non-conative emotion cannot motive 
any desire or volition. 

3. Volition as Activity 

There is one method of describing will, which 
calls a volition complete only when to the antici- 
patory idea, the desire, and the predominance of 
these, there is added the perception of the realiza- 
tion of the idea. Thus when I thought conatively 
of picking up the inkstand, and then proceeded to 
grasp it, I completed the volitional state by the 
perception of my fingers closing around the glass. 
A volition regarded from this point of view is more 
than a mere content or combination of content; 
it is a process, and cannot be represented by a cross- 
section of consciousness; it finds its individuality 
not in any specific sort of content, nor in any specific 
combination of content at any one time, but in a 
definite sequence of states of content. This is the 
doctrine of will as a psychological activity. It 
differs from the description of volition we have 
above given merely in the application of terms. 
All depends on the choice of the specific features 
of the complicated process which shall be designated 
by the term volition. 



274 A SYSTEM OF PSYCHOLOGY 

According to the system just stated, if the voli- 
tional process does not issue into fulfilment of the 
idea, but stops just before the last stage because 
of some external restraint, it is called determination, 
or wish. Thus, I determine that I will buy some 
paper when I next go down town; and I wish to 
go to the opera to-night. The difference between 
wish and determination depends on the anticipa- 
tory idea; if its intellectual factors include possibil- 
ity, the resultant state is determination; if possi- 
bility is not included, it is merely wish. The 
distinction between volition and determination is 
frequently only a matter of point of view: I try to 
catch a car, but miss it; from the point of view of 
catching the car my content was mere determina- 
tion, but from the point of view of my decision to 
run for the car, the state was volition. It is not 
advisable to give much attention to the activity de- 
finition of will, or to the problems growing out of it. 

4. Automatic Action 

In descending now to automatic action, we mark 
two stages; first, the elimination of desire, and, sec- 
ond, the elimination of the anticipatory idea. 

In carrying out a definite series of activities you, 
in many cases, do not will each one; even when 



ACTION AND WILL 275 

each act is separately ideated or undertaken, it is 
not desired. In an earlier chapter we have spoken 
of the spreading of the desire from the effect or end 
to the causes or means; but although this does occur 
in some cases, it is not essential. Thus, if I desire 
to get a book from the library across the street, I 
get up, put on my hat, go across and ring the bell 
of the elevator in the library, so performing a num- 
ber of acts which are ideationally initiated, but 
which individually are comparatively free from any 
appetitive factor. At the same time, in the course 
of getting my book I have performed several acts 
which are not even consciously initiated, although 
they are like the ones just mentioned, in that they 
might be initiated ideationally. Walking, for ex- 
ample, can be done by voluntarily placing the legs 
and body in the requisite successive positions, but 
usually it proceeds without either the desire or the 
idea of these positions. So it is with opening the 
door, avoiding a car, catching my hat just as the 
wind lifts it from my head, etc. These are all acts 
which may be involved in the total action of getting 
the book, and not only may take place mechanically 
in the proper order as if they were premeditated 
severally, but actually are more efficiently performed 
when they are mechanical. 



276 A SYSTEM OF PSYCHOLOGY 

If the movements essential to the carrying out of 
a series of activities are not perfectly uniform, but 
require variation to fit the environment (as in walk- 
ing on uneven surfaces, turning corners, stepping 
over gutters, etc.) these variations are introduced 
as perceptual reflexes; you see the gutter, for ex- 
ample, and the appropriate modification of the 
action of the muscles occurs without any further 
conscious intervention. The whole series of walk- 
ing movements may take place in the same way : my ' 
idea of getting the book may be succeeded by or 
include no idea of locomotion; the mere perception 
of my local situation may start my legs moving. 

An automatic act may be considered as a series 
of reflexes, perceptual, sensational, or physiological, 
in which each completed detail serves as a stimulus 
for the next. Thus, in walking, the shifting of the 
weight to the left leg may be the stimulus for the 
extension of the right leg, and so on : these two acts 
are themselves complex, and the series of muscular 
contractions which produces them are connected 
in a reflex way; when one is completed or reaches 
a certain stage, it sets off the next one. So, the 
whole process repeats itself automatically and is 
continued until inhibited by a new idea, perception, 
or sensation. It is probable that every function- 



ACTION AND WILL 277 

ally connected series of acts tends to pass in succes- 
sion from perceptual to sensational and physiologi- 
cal reflex-types, as regards the initiation of the 
particular acts. 

5. Instinctive Action and Learning 

The difference between an instinctive action and 
an automatic action or complicated reflex whose 
sequences and combinations are acquired, is simple 
in theory, although in practice discrimination is not 
always easy. The action of a young bird's wings 
in its first flight are instinctive — it never learned 
these actions. Your actions in waltzing are ac- 
quired — nature may have endowed you with the 
capacity for the essential movements of the feet and 
legs, but you had to learn the right combinations 
laboriously. The co-ordinating wing-movements 
of the fledgling may be initiated by the perceptions 
aroused when the bird first finds itself in the air, 
or they may be simply complicated physiological 
reflexes. On the other hand, the conclusion that 
either of these suppositions is true is at least pre- 
mature. It is possible that the flying may be initi- 
ated by ideas or even by the desire of flight. Other 
instances of complex actions which are instinctive 
— 2. e., not acquired, — are the feeding of young 



278 A SYSTEM OF PSYCHOLOGY 

birds and young mammals, and the first creeping, 
walking, and talking of young children. Our 
adult activities are based throughout on instincts, 
but in the development of these activities the ac- 
quired part comes to overshadow the instinctive. 
The turning of door-knobs, buttoning of coats, 
playing of violins, manipulating of complicated 
scientific instruments, the use of knives and forks, 
and so on ad infinitum, are actions initiated by the 
visual or tactual perception of certain objects; yet 
the combinations of muscular processes necessary 
to the accomplishment of these actions have been 
learned in past experience. 

Learning, in the domain of action, is in every case 
the combining of simple or relatively simple activi- 
ties which primarily occur instinctively or acci- 
dentally, for the accomplishment of something 
which none of the simple acts could compass. Such 
learning may proceed in one of three ways: 

(1) The combination may be entirely acciden- 
tal. The child may by chance make the "th" 
sound and associate the sound with the proper po- 
sition of the tongue and lips. The dog confined 
in the yard noses frantically at the gate until acci- 
dentally he trips the latch. If the animal is thus 
fortunate several times he may form an association 



ACTION AND WILL 279 

between the percept of the latch and the appropri- 
ate action. 

(2) Imitation. A child may learn a new pur- 
posive combination of movements at one stroke by 
seeing the action performed by somebody else. 
A peculiar hop or skip, the winding of a clock or 
mechanical toy; the buttoning of a garment; may 
be new, but performed fairly well the first time. 
By far the greater number of actions called imi- 
tative are, however, combinations of movement 
processes already learned, applying to specific ob- 
jects or purposes. Almost all of the imitative 
bodily postures and gestures fall into this class. 
Such activities as the putting on of clothes, eating 
with forks and spoons, and the great mass of 
practical activities in general, are learned slowly, 
and can be called imitative only if you wish to 
apply that term to every non-instinctive action. 

In learning by imitation, strictly so-called, the 
individual sees an act performed which he recog- 
nizes as a combination of certain more elementary 
processes of which he is already master, and then 
proceeds to perform this group of actions in the 
specific order and combination, for the first time. 
An act which is repeated by imitation must be 
one which the subject has previously performed.. 



280 A SYSTEM OF PSYCHOLOGY 

Imitation therefore presupposes a high state of 
development "mentally" and muscularly. All the 
components of the imitative act must be under 
ideational control; must be, in short, capable of be- 
ing voluntarily performed. If a child can say shoo 
and gar volitionally or as ideo-motor reflexes, he can 
succeed tolerably well in imitating your utterance 
of "sugar/* But if the child has not learned to 
say the word or the two syllables separately he can- 
not imitate it. It is possible, however, that if he can 
voluntarily say " thu,'* he may recognize a similar- 
ity of that sound to ",su" and make the substitution. 

Imitation has really a small place in the field of 
learning. In most cases it applies to the already 
learned. The mere incentive to learn furnished 
by our observation of what others actually do 
ought not to be called imitation: the term indicates 
either a perceptual or ideational reflex, in which the 
essential percept or idea is of a similar act performed 
by another person. 

(3) Conceptual analysis. At a higher stage of 
"mental" development, the individual is able to 
make new movement-combinations by a process of 
analysis. A certain situation is presented, which 
requires a number of movements in combination 
and succession, e. g,, the operation of a typewriter. 



ACTION AND WILL 281 

The beginner may without assistance discover the 
functions of the keys, the spacer, and the shift, and 
proceed to combine these functions; to alternate 
characters and spaces, to hold down the shift while 
printing a capital, and to hold down the shift and 
spacer while underlining or accenting. In all this 
combination there need be neither accident nor imi- 
tation, although all the movements here combined 
are put within the individual's power by instinct, 
and accident, assisted by imitation. Once learned, 
the combination becomes automatic, if the operator 
becomes in any wise expert. 

Although for aught we know the lower animals 
may "learn'' actions altogether without the aid of 
consciousness, man learns chiefly through volition. 
But the terminus of the learning process is that con- 
dition of efficiency in which volition, ideas, and 
other content of consciousness are eliminated as 
far as possible from the sequences of the action. 

6. Habit 

One of the most important features in the de- 
velopment of action is habit. Once a volition has 
occurred, it is easier for it to occur again. It may 
occur the first time after "hanging fire" a long time 
in the "strife" of opposing ideas, but next time the 



282 A SYSTEM OF PSYCHOLOGY 

strife is shorter. With each repetition the process 
is accelerated and made easier, until finally the idea 
alone will produce the action, and we have the first 
step toward automatism. If a series of actions 
occurs habitually in the same order, after suf- 
ficient time, not only the essential desires and voli- 
tion, but the ideas as well, will be eliminated and the 
series once started will unroll mechanically unless 
modified by new sensations; automatism will be 
complete. 

Habitual repetition may modify the action in 
another way. The sensory content which at first 
aroused the anticipatory idea and desire may become 
able to do the work alone, by the progressive 
elimination of the two factors mentioned, thus giv- 
ing rise to the acquired reflex. The sight of the 
letter put into your hands may be followed by the 
opening of the letter, even when you have neither 
idea nor desire of the act or its consequences. 

The instinctive reflex has been called an inborn 
habit. Whether the tendency to act in a certain 
way is, or is not, the result of the habits formed by 
preceding generations, the instinct is certainly on 
the exact plan of the habitual action, and can be 
understood only by beginning with the latter and 
working down to the former. Yet the order in 



ACTION AND WILL 283 

analysis is not necessarily the order in history, and 
we need assume nothing as to the mechanism and 
process in the development of the instinct. So far 
as any one knows, tendencies to think and feel may 
just as well be inborn as may tendencies to act, and 
hence we must be cautious in classifying any given 
act of the young animal as reflex, ideo-motor, or 
voluntary. 

Habit is an enormous factor in our psycho-physi- 
cal existence, and has received its due attention 
from the psychologists. But as yet no explanation 
has been found for the method of operation of 
habit. The building up of habit has been likened 
to the formation of channels by streams of water 
and to the wearing of paths by successive footsteps 
which erode the soil deeper and deeper. The laws 
of habit are sometimes stated in terms of "brain- 
paths,^' but we must remember that this form of 
statement is merely a carrying out of the analogy 
just mentioned, and means little in physiology. 
All we can do at present is to state the facts psycho- 
logically, and admitting that they have their physio- 
logical conditions, keep a sharp lookout for what 
may be discoverable concerning these conditions. 



284 A SYSTEM OF PSYCHOLOGY 

Note 

The "motor tendency of thought" may be ex- 
hibited in the case of a normal subject by any of the 
usual means for recording "automatisms." For 
instance, have the subject's hand resting on a plan- 
chette, or, better still, on a glass plate resting on 
three steel balls which roll on a second plate, the 
upper plate having attached to it a pencil which 
bears upon a strip of paper. Have a screen so 
interposed that the subject cannot see his hands nor 
the pencil and paper. Let him see you trace a line 
on the wall in front of him, or hear you describe such 
a line verbally. In nearly every case the subject's 
hands will move, as shown by the pencil record, in 
a way corresponding to the line. 

Buckle a strap around the subject's head (over 
the top of the head and under the chin), and fasten 
to the strap on top of the head a wooden point. 
Let the subject stand (with eyes closed) under a 
sheet of smoked paper supported at one edge and 
resting on the wooden point. Tell the subject to 
stand perfectly still, and mention to him interesting 
objects actually or suppositionally lying in certain 
directions from him, and he will be found to move 
in the designated direction, or the opposite, accord- 
ing to the nature of the object. 



CHAPTER XVI 

THE SELF, OR EMPIRICAL EGO 

One of the most obvious distinctions in the con- 
tent of experience is that between the self and the 
not-self; between the me and the remainder of the 
world. Several different distinctions have, how- 
ever, been described in terms of self and not-self, and 
the terms are even at the present day used in a 
variety of significations. Sometimes the terms 
self and not-self have been applied to an assumed 
substantial soul, and the world of experience re- 
spectively; sometimes to ''mind'' and its contents; 
sometimes to the content of consciousness and an 
assumed external reality. We are referring here to 
none of those distinctions. For Psychology, the 
self and the not-self are both content: with a self 
and a not-self that are not content we have practi- 
cally nothing to do, no matter what may be our ar- 
ticles of faith on the question of the reality of these. 

We have found in the content nothing but sen- 
sations, relations, and feelings, and possibly images. 
If this is a complete list of the kinds of content, then 

the self or '*me'' is made up of these factors, or at 

285 



286 A SYSTEM OF PSYCHOLOGY 

least can be resolved by analysis into them. We 
cannot rigidly prove that there is not an objective 
self sui generis which pervades, accompanies, or is 
somehow experienced along with the general con- 
tent. All that we really need to say is, that no one 
has been able to demonstrate such a factor in con- 
tent. When you analyze, the self reduces to the 
forms of content we have described, and no residue 
can be detected. The self must then be described 
either as certain factors of content in combination; 
or as a certain form of combination of content, in 
simultaneity and succession; or as both. How large 
a part the form of combination of content plays 
in the self is a problem too difficult to be taken up 
here, and is not important for our purposes. Under 
any plan of description the self is wholly content. 
The first elements we notice when we attend to 
the self and attempt to analyze it, are bodily sen- 
sations. Sensations of warmth, cold, and pressure 
from the surfaces, with sensations from the joints, 
muscles, and viscera; combine into a mass which 
is constantly present, even in the lighter phases of 
sleep. This mass is a part of the ^^me" in a pro- 
found sense. On the other hand, certain other sen- 
sations from the same organs are not fused with 
this mass, but stand off from it as something for- 



THE SELF, OR EMPIRICAL EGO 287 

eign. While we can make no very definite state- 
ment on this point, it Is probable that anything 
which gives a sensation a distinctive position, as, for 
example, relatively high intensity, sharp spatial or 
temporal limits, or strong associative connection, 
tends to separate it from the vaguer mass which is 
at the foundation of the self. 

The feelings are the constituents of the self which 
are next in importance to the sensations, and they 
are, apparently, without exception involved in the 
self. However you may feel — whatever feelings 
you may "have' ^ — these feelings are a part of you; 
to name them is to describe in part the sort of self 
you are — or "have'' — at that specific time. The 
emotions, which we have concluded are masses of 
unanalytically apprehended sensations and feelings, 
are necessarily also factors in the self. This fact 
was understood by various psychologizing philos- 
ophers long before the present theory of the emo- 
tions was elaborated. The emotions, they said, are 
modifications of the self, and hence of a different 
order from "perceptions" and "ideas." 

The self, furthermore, contains all the other sen- 
sations (and relations) which make up the per- 
ceived human body. The visual and auditory 
"sensations of the body" are included without re- 



288 A SYSTEM OF PSYCHOLOGY 

spect to their distinctness or sharp definition. The 
body, in short (as an experienced fact, not as a 
materialized supposition), is fundamentally the self. 
A striking demonstration of the truth of this state- 
ment is found in the uniformity with which all 
naturally developed religions which assume a per- 
sistence of the self after death ascribe to it a body 
of some sort. 

Psychic individuality, or self-hood, means thus 
more than mere capacity for experience. It means 
the existence of a specific, although complex, con- 
tent which is persistently present; which, although 
it changes its total character, changes slowly; and 
which hence is the standard against which all other 
content is measured. The self forms accordingly 
the basis for the perceived continuity of the ever- 
changing content. Its rhythmic variations with 
the solar day and the physiological condition serve 
as the clock of consciousness. When hungry, the 
idea of the normal steps for obtaining food are 
brought up through normal association. In the 
morning, the recurring associations with the morn- 
ing state of the self bring up the proper ideas for 
that time of day almost unfailingly. The intricate 
system of associative nexus which bind past experi- 
ences together and make our relatively orderly 



THE SELF, OR EMPIRICAL EGO 289 

mental life possible might be controlled in some 
other way, but as a matter of fact they are con- 
trolled by the particular associations of this bodily 
self with the other factors in the manifold. 

The self is by no means exhausted by the body 
and the feelings. Many things to which the body 
stands in a particularly intimate relation are ab- 
sorbed into the self. Family, business, and social 
relations, for example, tend to become relations 
within the self. 

The mass of habitually experienced content is the 
self. '^ Thoughts'^ are in some respects more im- 
portant than percepts. '*As a man thinketh, so is 
he,^^ is trite but largely true. The phases of per- 
sonality which are essentially habitual ways of 
thinking, or habitual sorts of thought content, we 
usually designate by the term ^* character.'' But 
the habitual trains of thoughts are, as we know, de- 
termined to a large extent by the feelings, and not 
only by mere feelings, but by emotional complexes. 
So that in the healthy individual, self, including 
character, is a rather coherent mass of content. 

In many cases an apparently normal individual 
possesses a double character. The church-going 
business man, on Sunday, for example, may really 
think admirable thoughts, which may be allowed 



290 A SYSTEM OF PSYCHOLOGY 

to find expression in suitable action. On other 
days he thinks only of business, and his actions 
are quite at variance with his Sunday doings. It is 
quite probable that he builds up a double set of 
sensational selves, too, one of which is associated 
with each of the thought-complexes. The evidence 
for this assumption is found in the fact that his 
facial and bodily expressions change with his change 
of character, and give grounds for suspecting more 
profound organic modifications. Certainly, he has 
two sets of emotional habits. He really is not a 
hypocrite, in an ethical sense, but is a diseased per- 
son, a monster with two selves. 

There are an indefinite number of possible prin- 
ciples of bifurcation of the self, and these bifurca- 
tions may be incipient or thorough-going, that is, 
they may affect only the habits of thought, or may 
affect the bodily sensations. A man may be pure- 
minded at certain times, and lewd at others; he 
may be a buoyant optimist and a downcast pessi- 
mist; and so on ad infinitum. And any of these 
divisions of character may by the gradual forma- 
tion of associations become a cleavage affecting 
practically the whole personality. There may be 
three of these fractional personalities, or even more, 
in a given case. 



THE SELF; OR EMPIRICAL EGO 291 

It is probable that none of us are completely free 
from the taint of divided personality, but most of 
us need not fear any disastrous developments. The 
dangerous eases are those in which one side of 
the character has been long repressed, but is still 
smouldering. The individual, for instance, gives 
rein usually to the moral member of his team of 
selves, and allows the lewd character to express itself 
only at the infrequent times w^hen he thinks he is 
safe from the observation of his associates. In this 
case, some change in the bodily condition, deeply 
stirring the whole self, gives the repressed self its 
chance, and flaring up, perhaps suddenly, it be- 
comes dominant. In extreme cases the sets of 
ideas constituting the character side of the previously 
dominant self, and the other groups of ideas asso- 
ciated with these, are completely lost, and hence the 
patient not only evinces a seemingly new person- 
ality, but actually loses the memory of years of his 
life. These sudden changes are called alterations 
of "personality y and in the cases where there is re- 
peated change from one personality to the other 
or others, the terms alternation of personality and 
alternating personality are applied. These cases 
will be further discussed in Chapter XIX. 



CHAPTER XVII 

THE DEGREES OF CONSCIOUSNESS 
I. Consciousness, Attention, and Vividness 

Up to this point we have restricted our discussion 
as far as possible to the objects of v^hich we are con- 
scious and the behavior of these objects, that is to 
say, to the items and processes of content. Now we 
must undertake the seemingly impossible task of 
examining consciousness itself. How it is possible 
to examine consciousness, and in what consists the 
operation which we thus designate, are problems 
which are beyond the scope of the present under- 
taking. As a matter of fact we do study or discuss 
consciousness, whether directly or indirectly. 

For practical reasons we have somewhat antici- 
pated the discussion of kinds of consciousness, and 
have entertained the possibility of distinguishing 
two kinds; the consciousness of content "present^* 
(intuition) and the consciousness of content not 
"present^' (imagination). The fact that neither of 
these can exist separately, but that what we really 
find is consciousness of a content partly present and 

partly not present, is no obstacle to the analytical 

292 



THE DEGREES OF CONSCIOUSNESS 293 

consideration of the two kinds, and establishes no 
presumption against the value of such consideration. 
The case is precisely the same as in the discussion of 
sensation as such. At the present time, however, 
there seems to be no practical advantage in the 
lengthy discussion of these or other hypothetical 
sorts of experience. 

Consciousness varies in degree. One extreme of 
the range of variation is commonly known as a high 
degree of attention, or concentration of attention. 
The other extreme is inattention, to which the 
term subconsciousness is also applied. The general 
designation of attention is thus given only to the 
higher degrees of consciousness. If referred to the 
content, the degrees of consciousness are degrees 
of vividness, which is sometimes called clearness. 
Thus, to say that I attend to a sensation or percept 
is equivalent to saying that the sensation or per- 
cept is vivid. The content not attended to is non- 
vivid. In a somewhat better use of the term we 
speak of a high degree of vividness and a low degree 
of vividness in the two cases mentioned. Whether 
any content may properly be said to be not vivid 
at all is a matter which we will consider later. 

The term attention properly signifies a condition 
or state of consciousness itself. Sometimes it is ap- 



294 A SYSTEM OF PSYCHOLOGY 

plied to a certain content as well. When I attend 
to a sound, I am conscious of an adjustment of 
head, and possibly of a change in the tension of the 
muscles of the middle ear. When I attend to a 
light, I am conscious of an adjustment of the inter- 
nal and external muscles of the eye. In addition, 
in both cases, there are sensations of strain from 
the muscles of other parts of the body; the chest, 
the face, perhaps, also, the arms and legs. All these 
factors are sometimes included under the head of 
attention. Again, the motor adjustments as ap- 
prehended by another individual are referred to by 
the name attention. A dog, for example, is said to 
^* attend'' to an object when his sense-organs are so 
adjusted as to give him the best condition for stimu- 
lation by the object, although we make no assump- 
tions as to the dog's consciousness. The student 
may later find it difficult to escape falling into con- 
fusion on account of the varying uses of the term 
by different authors. 

The total content of consciousness at any given 
moment is conventionally spoken of as the "field 
of attention" or "field of consciousness." It is 
likened to the visual field, i, e,, to the mass of visual 
content "spread out" before the eye at any given 
time. This analogical treatment is quite defensi- 



THE DEGREES OF CONSCIOUSNESS 295 

ble, since we may consider visual content as typical 
of all content. In this field of consciousness, as 
spatially analogized, we may represent the highest 
degrees of vividness at the centre, and the lesser de- 
grees by zones at different distances therefrom. 
The centre of this conventionalized field is called 
the " focus," and the most remote portions are called 
the "fringe" of consciousness. 

A question which naturally arises at this point is 
as to the number of discernible degrees of atten- 
tion. Are there three degrees: a focus, a fringe, 
and an intermediate region ? Or are there only two 
grades, focal and non-focal ? or are there four, five, 
or more grades ? This question may be left open 
for the present, as no adequate means of determining 
the number of degrees has yet been found. 

2. Vividness and Intensity 

Vividness is sometimes confused with intensity. 
Hence it is necessary to distinguish carefully be- 
tween the two, as well as to consider their connec- 
tions. Suppose you are talking to a friend, while 
a large clock is ticking loudly on the mantel. The 
clock, we will suppose, is in your range of vision, 
and the ticking is plainly audible, but neither is of 
much consequence in your total content until your 



296 A SYSTEM OF PSYCHOLOGY 

friend remarks "what a curious old clock! '^ Im- 
mediately the clock (visual and auditory) becomes 
vivid, and the features and voice of the person be- 
come reduced in vividness. Has the intensity 
(loudness) of the ticking, or the brightness of the 
visual sensations increased? Not to any appreci- 
able extent; neither has the loudness of the speaker's 
voice decreased, nor the intensity of the visual pres- 
entation of his features waned. The "focus of 
consciousness '^ has shifted, or rather, the impres- 
sions have shifted as regards the focus, but changes 
in intensity, if they occur, are purely accidental, and 
are due to such factors as change in position of the 
eyes, or in the tension of the ear-muscles. (We are 
not considering, of course, the possible actual changes 
in the physical intensity of the voice, or in the il- 
lumination of the room.) 

Attempts have been made to determine the ef- 
fects of vividness on intensity of sensation, with re- 
sults which are seemingly contradictory, but really 
harmonious. The characteristic method of exper- 
iment is to find what intensity of a sensation of given 
quality will be judged equal to the intensity of a 
sensation of the same quality which immediately 
precedes or follows it, when the subject "gives full 
attention '^ to one of the pair, and is "distracted'* 



THE DEGREES OF CONSCIOUSNESS 297 

somewhat from the other by accompanying sensa- 
tions, or by performing mental labor, as adding or 
multiplying, or repeating verses. The other con- 
ditions are kept as constant as possible for both sen- 
sations. 

Some experiments have apparently shown that a 
sensation to which full attention is given, is judged 
equal to a sensation which is less vivid, when the 
intensity of the more vivid sensation is slightly less 
than that of the less vivid one. Other experiments 
have shown, on the other hand, exactly the reverse. 
Hence we have had some experimenters claiming 
that attention to a sensation increased the intensity 
while others have claimed that the attention de- 
creased the intensity. 

As a matter of fact, these experiments have no 
bearing at all on the question of the relation of in- 
tensity and vividness. They simply bear on the 
judgment of relative intensity, which is a different 
matter. Similar results may be obtained in the case 
of judgment of size, as when two squares are com- 
pared; and in the case of judgments of quality. 

That intensity affects vividness we cannot deny. 
A rapid change in the intensity of any sensation — 
either increase or decrease — tends to bring it to the 
focus of attention. Of several sensations or sen- 



298 A SYSTEM OF PSYCHOLOGY 

sation-complexes, the most intense will probably 
have strongest claim on the attention, other things 
being equal. Other factors are, however, so much 
more important that little effect is produced by the 
mere intensity. 

3. Factors Determining Vividness 

A. Sensational Factors. — Intensity, we have just 
considered. Ex tensity and area may operate in 
the same way. The larger tends to obscure the 
smaller. Of two pictures hung on the wall, equally 
lighted, and not essentially different in coloring, 
character of subject, etc., the larger will get the at- 
tention first. Of two touches, two tones, two pains, 
similar statements may be made. Quality may 
have some influence. Red, for instance, may at- 
tract the attention more than blue. Visual sensa- 
tions usually take precedence over auditory, and 
olfactory over both. All of these sensational factors 
are of slight importance as compared with the others 
mentioned below, and their effects may be due to the 
feeling factors which accompany them. 

B, Affective Factors. — In the case of feelings, 
intensity is more important than in the case of sen- 
sations. The more intense feelings always have 
a great advantage in vividness. Perceptions and 



THE DEGREES OF CONSCIOUSNESS 299 

ideas attended by intense feeling are therefore usu- 
ally found to be occupying the focus to the exclu- 
sion of complexes with weaker feeling-componentis, 
in accordance with the association factors mentioned 
below. Whether one sort of feeling is more ef- 
fective than another in this way, we have no grounds 
for affirming or denying, since it is not possible to 
equate intensities of two sorts of feeling. We can 
decide that the pleasant feeling of one complex is 
approximately the same in intensity as the pleasant 
feeling of another, or at least not appreciably dif- 
ferent, but comparison of pleasant feeling with un- 
pleasant feeling in degree of intensity is definite only 
when one is noticed to be relatively much greater 
than the other. 

C, Association Factors, — The whole matter of 
the rise of ideas through association is one of vivid- 
ness. One percept or idea occupying the focus of 
consciousness tends to bring in its associates. If 
the primarily focal content forms with its associates 
what we call a single object, the associates are sim- 
ply added to the focal content. If the associates, 
on the other hand, form objects distinct from the 
primary content, the latter drops out as one of the 
former comes in. The feelings associated with a 
certain percept or idea come under the first rule, 



300 A SYSTEM OF PSYCHOLOGY 

hence the tendency above noted, for the content 
having the more intense feeling associated with it to 
gain the ascendency over the content with less in- 
tense feeling associates. The statement that two 
distinct objects are attended to successively applies 
only to the case where one of them occupies the 
focus before the other is called up through associa- 
tion. That two different objects may occupy the 
focus simultaneously under certain circumstances 
is perhaps true, but is to be considered later. It 
must be noted, however, that when several distin- 
guishable objects form a functionally connected 
group, as a hunter and his prey, a church and the 
congregation, they may constitute at a given time a 
single co-ordinated content, although from other 
points of view they may constitute distinct, even 
conflicting, contents. 

D, Relational Factors, — Relations determine viv- 
idness of related content, inasmuch as they form 
nexus among the factors of content. Nothing need 
here be added to the discussion of the function of 
relations in association. On the other hand, re- 
lations seem to have a distinct advantage in vivid- 
ness over sensorial content. In a focal content the 
relations are usually the most vivid part. This is 
especially true of " thought. '* Our thinking con- 



THE DEGREES OF CONSCIOUSNESS 301 

stantly tends to be conceptual, rather than of the 
sensory-imaginative type. In actual perception the 
situation is often reversed, and the sensational fac- 
tors are focal at the expense of the relational. 

E, Other Factors, — Anything singled out, or spe- 
cifically characterized objectively, is thus made lia- 
ble to especial vividness. The first and last letters 
of a written word, a note or word marked by a pre- 
ceding or succeeding pause, a trilled or syncopated 
note, a bit of color in the scenery unlike the sur- 
rounding hues, an element having a humorous sig- 
nificance or any other emotional coloring widely 
different from that of other elements — these receive 
especial attention. The list is indefinitely long. 

4. Attention and Interest 

Interest is sometimes named among the condi- 
tions of attention. That the feeling we have earlier 
referred to by the name of interest does predispose 
to vividness the content associated with it, is indis- 
putable. The same is true of any emotion or emo- 
tional factor. 

When, as is sometimes the case, attention is 
treated as exclusively a matter of interest, the term 
interest is not used to designate an affective con- 
tent, but an abstract potentiality. Interest ascribed 



302 A SYSTEM OF PSYCHOLOGY 

to any possible object means in this case the fact 
that when that content arises it will probably be 
vivid (^. e,, attended to), and that the probability 
of the rise of that content is relatively high. Inter- 
est is in this sense by no means a cause of attention, 
but a mere abstraction from the observed or proba- 
ble course of attention-changes. 

It is so easy to shade from one meaning of the 
term interest to another, that the student must be 
on the alert when following any exposition of the 
psychology of attention in which the term is given 
an important place, lest he be led to accept as 
analysis what is merely a confusion of thought. 

5. Vividness and Practical Advantage 

The greater efficiency of conceptual thought as 
compared with thought which depends more largely 
on the sensory image can hardly be disputed. By 
efficiency we mean here the celerity and accuracy 
with which a conscious result is obtained, as in 
solving a problem, or making a decision. Hence, 
the tendency to greater vividness of relations as com- 
pared with "imaged^' sensations can be regarded 
as having arisen or having been conserved because 
practically advantageous. The same interpreta- 
tion can be brought to bear on every general con- 



THE DEGREES OF CONSCIOUSNESS 303 

dition of vividness. The objects which are most 
intense and most strongly charged with feeling are 
the ones to which it is, in general, mentally advan- 
tageous to attend. 

6. Judgment 

The distinction between concept and judgment 
is entirely a matter of relative vividness among the 
factors of these complexes. If I have the concept 
of a horse, with a definite relation of horse to hay 
especially vivid, I have (psychologically) a judg- 
ment which I express (logically) by saying that the 
horse eats hay. 

In general, a judgment involves two concepts; 
but again, in general, no concept stands alone. I 
cannot conceive a horse without several other sub- 
sidiary concepts entering into the content, and, in 
the judgment, one of the subsidiary concepts, with 
a definite system of relations linking it to the central 
concept, simply becomes more vivid. 

From the preceding it ought to be plain that the 
function of the judgment is the growth of the con- 
cept. If the relation emphasized by the judgment 
is already a part of the concept, the judgment is 
analytic. For me to form the judgment which I 
express logically by the proposition, "Water lays 



304 A SYSTEM OF PSYCHOLOGY 

dust/' adds nothing of value to my mental content 
or functions. My concept of water already in- 
cludes the relations to desiccated substances, which 
I call wetness. But when I first discovered that 
water can be produced by the union of two gases, 
the judgment constituted by my apprehension of 
that (to me) new relation of water was synthetic. It 
permanently modified the concept. Included in 
my concept of water from that time forth was that 
relational complex which I express when I say, 
" Water is composed of oxygen and hydrogen." 

7. The Scope of Attention 

How many things — how many functionally dis- 
tinct factors in content — may be attended to at 
once? In general, only one, as you may verify 
introspectively by the aid of a little experimenta- 
tion. Arrange several articles on a table in front of 
you, and if a clock is ticking, or a gas flame audi- 
bly roaring in the room, and if the finger is pressed 
firmly on some hard object — e. g., the edge of a 
paper-cutter — you will have a sufficient range of 
objects. Attend to one of the content factors, and 
the others coincidently recede from the focus of 
consciousness. Seldom, if ever, can you succeed 
in retaining two of the objects at high vividness. 



THE DEGREES OF CONSCIOUSNESS 305 

When an object — an ink-bottle, for instance — 
IS low in vividness it may be rather uniformly vivid. 
But when the focus of attention shifts to the object 
it is apt to fall upon some limited feature. Thus, 
when attending to the ink-bottle, you will find that 
it is the top, or the bottom, or the cork, or the label, 
or the ink, or some such detail which is focal. The 
other portions of the bottle are less vivid. We may 
say in general that the content occupying the focus 
of attention is relatively simple. But, in a content 
which does at one time occupy the focus, we may 
later (in memory) discover many details. These 
details, in the later analysis, occupy the focus suc- 
cessively. 

Several relations can be focal simultaneously only 
in so far as they join in a single concept. Two dis- 
tinct concepts are probably never present at once, 
even in the formation of a judgment. 



CHAPTER XVIII 

THE TIME RELATIONS OF CONSCIOUSNESS 
I. Presentation and Image 

In earlier chapters we have concluded that what 
is commonly known as the image is not different in 
kind from sensation, but that the difference is in the 
way of being conscious. The difference, in short, 
is in the time factor. If we are now conscious of 
what is now here, the content is called sensation; 
if we are now conscious of what was formerly here, 
the content is called image. The time factor needs 
somewhat further elaboration. 

There are two distinct temporal phases of a pres- 
entation, which may be provisionally distinguished 
by reference to the assumed cortical process. The 
presentation does not cease when the cerebral proc- 
ess ceases. We may call the phase of sensation in 
which the cortical process is active the primary 
phase, and the phase after the practical cessation 
of the cortical process the secondary phase. This 
secondary phase of the presentation is distinct from 

the image. 

306 



THE TIME RELATIONS OF CONSCIOUSNESS 307 

If we observe a regular series of brief visual or 
auditory sensations — clicks of a telegraph sounder, 
or flashes of light — we find that they may be so ar- 
ranged that the successive sensations do not fuse; 
each is separate and distinct from the preceding 
and succeeding ones; but several may be simul- 
taneously present to consciousness. If four suc- 
cessive sounds, for example, are given in one sec- 
ond, they may be apprehended simultaneously, 
although not as simultaneous. You may easily 
demonstrate this, employing taps of your finger or 
pencil on the table. When the fourth tap is in its 
primary phase, the preceding three must be in their 
secondary phases. If they were yet in the primary 
phase, the four would fuse into one continuous 
sound. Compare the four just when the fourth 
arises with the same four a few moments later (as 
memory images), and you note the difference at 
once. As apprehended simultaneously, they are 
sensations and not images. 

This peculiarity of sensations is of great impor- 
tance in practical life — as, for example, in " taking'^ 
telegraphic messages, where the operator is con- 
scious of a sequence of dots and dashes as a whole, 
instead of having to carry the first part of a letter 
in memory until the last arrives. In spoken and 



308 A SYSTEM OF PSYCHOLOGY 

written language, too, this power of consciousness 
is of enormous importance. If you were listening 
to the preceding sentence you would not have to 
understand " enormous ^^ and carry it over in 
memory to modify "importance"; you would 
grasp the two literally together with a vast saving of 
mental process. In addition to the practical con- 
sequences of the secondary phase of sensation we 
find an important aesthetic factor in rhythm, which 
is made possible by it, and to the discussion of 
which we shall proceed in a moment. 

This apprehension, simultaneously, of factors 
which are apprehended as non-simultaneous, is 
described by the term, "the specious present.'^ 
The present moment, referred to content alone, 
stands as a mere inextended point dividing the 
past from the future. Since mathematics and logic 
must regard time altogether from the point of view 
of content, we have come to regard this as the real 
present. Hence, the term "specious present'^ 
(apparent or seeming present) applied to the pres- 
ent of consciousness.^ But this "specious" pres- 



^ This explanation of the term '^specious" as applied to the 
present is in strict accordance with the intention of Mr. E. R. 
Clay, who first used the term. Cf. James, Principles of Psy- 
chology, vol. I, pp. 606 ff. Other explanations (as that of the 
Century Dictionary) are obviously erroneous. 



THE TIME RELATIONS OF CONSCIOUSNESS 309 

ent is just as "real'' as the other, and there is ab- 
solutely no confusion between the two presents. 
Because I apprehend the successive terms A, B, C, 
D simultaneously, I do not necessarily apprehend 
them as simultaneous. 

2. Rhythm 

A fairly regular sequence of stimulations — clicks, 
taps on the skin, flashes of light, etc. — does not 
usually give rise to a uniformly progressing series 
of sensations. The greater part of our sensations 
belong in definite groups, as in the case of words of 
language, and the grouping habit is so thoroughly 
ingrained in us that we group objects which have no 
intrinsic demands for such treatment. 

Suppose we allow water to drip slowly from a 
small tank onto a tin plate, producing thus a dis- 
tinct noise for each drop. Let the rate of flow — 
^. e,, the rapidity of the succession of drops, be con- 
trollable. Suppose at first we choose a rate of 
between two and four drops a second. In listening 
to the perfectly uniform series of sounds thus pro- 
duced, you will find that very seldom does it pro- 
ceed monotonously. In most cases the sounds are 
automatically grouped in twos, threes, fours, or sixes. 
The exact numerical size of the group will depend 



310 A SYSTEM OF PSYCHOLOGY 

on the rate, the intensity, the Hstener, and on sug- 
gestions he may get from other processes he is ex- 
periencing or has experienced; as the ^*clickety- 
click" of the street-car which passed the building 
a moment or two before. 

The listener can easily give himself suggestions 
as to the grouping. If he thinks of hearing a 
"three-group'' the drops will usually organize 
themselves in that form. The chief limitation is 
that the groups will in general not extend over two 
or three seconds, although occasionally larger 
groups are formed. This temporal limit seems to 
be the span of consciousness, or the limit of the 
"specious present." Another limitation is in the 
number of the sensations; too many in a specious 
present give rise to confusion and abolish regular 
grouping. 

If the terms of the series are absolutely uniform 
in the case of the water-drops, and if the degree of 
attention is fairly constant, the grouping depends 
altogether on the time relations of secondary phases 
of the sensations. \Mien the final term of a group 
arises the foregoing terms of that group are still 
present; with the arrival of the first term of the 
next group the group just completed disappear from 
consciousness as presentations — the slate is washed. 



THE TIME RELATIONS OF CONSCIOUSNESS 311 

as it were. This sort of a rhythm is apparently due 
to the periodic contraction of the specious present, 
occurring at the beginning of each group. 

In many cases attention is not uniform. The 
drops may be heard in groups of four, for example, 
and the vividness of the first drop may be higher 
than that of the succeeding three. This is "sub- 
jective accent ^^ properly so called. 

The rhythm is much more distinctly and readily 
developed if "objective accent'^ is permitted. If, 
for example, by holding the finger on the tin plate 
on which the drop falls during the time of three 
drops, and lifting it for the fourth, the intensity 
of the fourth drop is made relatively higher than 
that of the others, the drops will tend to fall into 
groups of fours, the accented drop usually being 
the first of each four. Various devices are em- 
ployed for producing series of auditory, visual, and 
tactual sensations, and if these devices are so ma- 
nipulated that periodic variations in intensity, ex- 
tensity, duration, quality, or local sign are intro- 
duced, these variations serve as accents to determine 
the grouping. Periodic variations of the time rela- 
tion of the stimuli may also produce the same effect. 

With objective accent the periodic shrinking of 
the specious present takes place just as when there 



312 A SYSTEM OF PSYCHOLOGY 

is no objective accent; and the groups are usu- 
ally eliminated as wholes. If the groups are very 
short two or even three groups may be elimi- 
nated simultaneously, the contraction of the spe- 
cious present taking place with every second or 
third group. 

An important source of objective accent is found 
in muscular sensation. Very often, when there 
seems to be a purely subjective accent, it will be 
found that the stimulations are accompanied by 
slight muscular contractions in finger, arm^ throat, 
chest, or elsewhere, and these are accented by varia- 
tions in intensity, so that the grouping of the ex- 
ternally presented sensation is really directed by the 
accenting of the muscular sensations. It is pos- 
sible that pure subjective grouping is a very rare 
occurrence. 

Rhythm is important in music and in poetry, 
especially in the former; the span of consciousness 
demanded by the rhythmic groups has a large share 
in the determining of the emotional character of 
the composition. A short musical unit tends to 
light, vivacious, or joyful effects, irrespective of the 
rapidity of succession of notes, or of the melodic 
intervals employed. A unit which "draws out'^ 
the specious present slightly beyond the normal 



THE TIME RELATIONS OF CONSCIOUSNESS 313 

length produces a sombre effect. A still longer unit, 
which is divided between two not long spans of 
consciousness, gives an effect which is solemn, but 
not sad. Specific effects are produced by units of 
such length that two occupy a long span or a short 
span. All these effects are modified — sometimes 
counteracted — by the other musical factors intro- 
duced by the composer. In music of the so-called 
" intellectuar' sort there is no regular relation be- 
tween the musical unit and the span of conscious- 
ness; the unity here is intentionally ideational 
and does not appeal to the average hearer, who is 
baffled in his natural attempts to fit musical unit to 
specious present, and only by repeated experience 
acquires the other method of appreciation. 

3. Duration of Attention to Continuously Presented 

Sensation 

The rhythmic variation of the span of conscious- 
ness which we have just discussed has to do only 
with sensations of an intermittent nature. We must 
now consider cases where the stimulus is continu- 
ous and, hence, the sensation is continuously pre- 
sented. Such a case is afforded by the note of a 
steadily vibrating tuning-fork, or the noise of a small 
stream of water. 



314 A SYSTEM OF PSYCHOLOGY 

In most cases these continuous noises, if rather 
loud, persist in the focus of consciousness for some 
time; perhaps for minutes, perhaps for hours. 
After awhile, however, the sound may become mar- 
ginal. The duration of a continuously presented 
sensation or sensational complex in focal conscious- 
ness depends on the rise of other sensations or 
ideas which may take its place. If you sit beside 
a water-fall with your mind at rest, the purl of the 
water may continue vivid for hours, or if temporar- 
ily obscured by the other presentations of nature or 
by fleeting ideas, returns quickly to its place. But, 
if you have a problem to solve, a book to read, a 
friend to talk with, or a hill-side to watch for game, 
the water-fall quickly becomes an inconspicuous fac- 
tor in the total field of consciousness. So it is with 
all other presentations. The intense stimulus may 
force the sensation into the focus for awhile, but 
finally the mere intensity becomes ineffective. 

The effect of habituation in eliminating the per- 
sistent sensation from attentive consciousness may 
be illustrated in a great many ways. The noise 
of the street which annoys the countryman stay- 
ing at your house is practically unnoticed by you; 
yet the ear does not lose its sensitiveness to the noise 
as does the nose to a continuing odor. During the 



THE TIME RELATIONS OF CONSCIOUSNESS 315. 

greater part of the day you hardly notice the sensa- 
tions aroused by the rubbing of your clothing on 
your skin; to a savage first clothed the sensations 
are intolerable. The lights of the lamps and win- 
dows on the street at night you scarcely notice at 
all; your rural friend is so attentive to them that he 
can hardly converse with you. We find, in general, 
in addition to the physiological adaptation which 
protects us from continued stimulation, a sort of 
protective adaptation of consciousness itself by 
which the persistent sensations not eliminated by 
physiological adaptation are relegated to the mar- 
ginal consciousness, unless they exercise solicitations 
other than those of mere intensity. 

The relegation of intense sensations to marginal 
consciousness through habituation is realized also 
in case of sensations not continuous, but which 
are repeated at frequent intervals. The train rush- 
ing by every half-hour; the clock striking every 
hour; even a church-bell ringing at morning, noon, 
and night; soon becomes without power to disturb 
the focus. If the interval between stimulations is 
long this habituation does not occur. Thus, a 
church-bell ringing only on Sunday mornings may 
be as vivid at the end of a year's disturbance thereby 
as at the beginning. 



316 A SYSTEM OF PSYCHOLOGY 

4. The Fluctuations of Minimal Sensations 
Sensations of uniform minimal intensity show a 
peculiar intermittence in presentation, to which is 
commonly applied the confusing name "fluctua- 
tions of attention/^ If one attempts to listen to a 
sound, for instance, which is physically constant 
and just above the threshold, he finds that the sound 
is clearly discernible for short periods and in inter- 
vening periods is not to be heard at all. The times 
of absence and presence may vary from a fraction 
of a second to over ten seconds. Faint sensations 
of certain other modes behave in the same way. A 
small gray spot on a background slightly darker, 
for example, will appear and disappear periodically 
under the best obtainable conditions of attention and 
accommodation. 

It has been supposed that these fluctuations are 
due to varying states of muscular adjustment in the 
end-organs, and, in fact, slight changes in accom- 
modation have been found to accompany the visual 
fluctuations. This theory is excluded by experi- 
ments which absolutely preclude any adjustmental 
variation and which yet find fluctuations occurring. 
The theory which is most probable assumes the 
physiological cause to be a periodic variation in the 



THE TIME RELATIONS OF CONSCIOUSNESS 317 

functioning of the nervous mechanism; either of 
the nerve terminals of the end-organ or of the cor- 
tical cells. The variation, if it occurs, is very slight, 
for no periodic increase or decrease in intensity of a 
sensation from a physically constant stimulus con- 
tinuously above the threshold is discernible.^ 

The phenomena in question are therefore not 
"fluctuations of attention^' in a sense in which that 
expression would naturally be taken. If the at- 
tention does actually shift from a sensation under 
observation, the disappearance of the sensation can- 
not be noted unless the disappearance comes be- 
fore the shift or after the attention returns. Yet 
the fluctuations are, in another sense, those of 
"attention," for the essential condition of the ex- 
periment is that the attention shall be to the image 
of the presentation in the intervals when the sen- 
sation is not intuited. 

The difficulty of distinguishing between the sen- 
sation and the image in the case where the stimula- 
tion is minimal enormously complicates observa- 
tion. In certain cases the observer is unable to 
distinguish at all, as is shown by his continuing 
to report the sensation long after the stimulus has 
been suspended completely but gradually. In such 
* This is true for auditory sensations, at least. 



318 A SYSTEM OF PSYCHOLOGY 

cases the characteristic fluctuation cannot be ob- 
tained; the sensation seems either present all the 
time or absent all the time. 

5. The Selective Fluctuations of Vividness 

When several complexes are presented they are 
apt to occupy the focus alternately. As I gaze at 
the desk before me my attention is centred now on 
the ink-bottle, nov^ on the pile of books, now on the 
ink-bottle again, now on the drop-light, now on the 
stack of letters. Even when I attempt to attend 
continuously to the ink-bottle I find that I am at- 
tending to it only for short periods, the focus being 
occupied by various other things in the intervals. 
Not visual presentations alone jostle the presenta- 
tion of the ink-bottle. Auditory, tactual, olfactory, 
and organic presentations take their turn. Ideas 
also flip in and out to the detriment of my study 
of the ink-receptacle. 

This periodicity of focal consciousness is one of 
its most uniform characteristics. In general, we 
can attend to anything only by a succession of short 
periods. This holds for ideas, of course. Try to 
think of any one thing and see how intermittently 
you succeed. 

Many striking illustrations of the selective flue- 



THE TIME RELATIONS OF CONSCIOUSNESS 319 

tuations of attention are easily available. Retinal 
rivalry is one such. Place in a stereoscope two sim- 
ple pictures which are radically different; a num- 
ber of concentric circles in one, and a number of 
parallel lines in the other; or two large letters, or 
two fields of different colors. On looking through 
the stereoscope in the usual way — one eye seeing 
each card — it will be found that the two figures or 
two colors are seen alternately. Sometimes both 
of two colors will be seen, but in different parts of 
the field, or parts of both diagrams will be seen 
simultaneously.^ 

The "stair-case figure,^' "tumbling block figure,'' 
and other illusions of "reversible perspective'' are 
also illustrations of fluctuations of attention. These 
are simple figures so drawn that the space relations 
are ambiguous. Thus, in Figure 13, the skeleton 
chair may be seen either facing you or facing away 



* If the two pictures are so arranged that no detail of one 
occupies a retinal point corresponding to a point of the other 
eye, occupied by a detail of the other picture, the two may 
combine. Thus, if a figure before one eye has an open space 
in the centre, and a smaller figure be presented to the retinal 
area of the other eye corresponding to this space, the figures 
may be seen combined. Some observers report binocular 
color combinations; red presented to one eye, and blue to the 
other, giving purple, etc. But this observation may for the 
present be doubted. Complementary colors will give gray, 
because adaptation to the two takes place rapidly. 



320 



A SYSTEM IN PSYCHOLOGY 



from you. After seeing it both ways it is practically 
impossible to see it either way continuously. At- 
tempts have been made to connect these changes 
with eye-movements, or spatial shifts of attention, 
i. e,y from one point of the figure to another. At 
certain times the chair will face you while you at- 



y 








^L 


( 


1 


/ 




/ 




Q 




J 




a 





Fig. 13. 



tend to the corner at a, and reverse its position when 
your attention shifts to b. This is as if the point 
fixated tends to become the near point. But the 
same shift of perspective may be produced with the 
opposite shift of attention; all depends on which 
habit is formed. In general, any such objective way 
of determining a shift of the perspective operates 
through association. You expect to see the figure 
in a certain position when a certain change is made. 



THE TIME RELATIONS OF CONSCIOUSNESS 321 

or you have uniformly observed it in a certain posi- 
tion with a certain direction of attention. Hence, 
the result. 

The percept based on the lines of the reversible 
perspective figure is largely reproduced. The sim- 
ple lines of figure 13, for example, are associated 
with other features of chairs in both positions equally 
well. We have, therefore, a selective fluctuation of 
the two reproduced factors, first, one uniting with 
the presented content, and then the other taking 
its place. The exact moment of the transformation 
may be determined by such factors as shift of eye 
in any direction, provided the shift has become 
associated with that particular change. 

Figures 14 and 15 show a sort of fluctuation akin 
to that of the reversible perspective figures. After 
looking carefully at a and h (of either figure), c 
alone will probably be seen alternately with the 
aspect of a and &. 

Fluctuations of perception based on ambiguous 
impressions of senses other than visual might be 
produced. These ambiguous impressions are, how- 
ever, not so simply obtainable in the other sense- 
realms. One experiment may be made in the fol- 
lowing way: Obtain a revolver with round barrel 
and a bottle having a neck of the same diameter 



322 



A SYSTEM OF PSYCHOLOGY 



and thickness as the muzzle of the revolver. Press 
the muzzle of the revolver and the mouth of the 
bottle alternately on the temple of the subject (first 




Fig. 14. 






Fig. 15. 

removing the cylinder of the revolver!), allowing the 
subject to see the object each time. Then, with 
the subject's eyes closed, press either one against 
the temple and in many cases he will perceive the 
ring of pressure and temperature sensations alter- 
nately as the pistol and as the bottle. 



THE TIME RELATIONS OF CONSCIOUSNESS 323 

6. The Conditions of Constant Attention 

Constant attention to one object in a normal con- 
dition means one of two things: either the object 
is intermittently in the focus or else the object in- 
volves several discriminable details which occupy 
the focus alternately or in succession. To attend 
in actual continuity to a bare sound or color, even 
to one of considerable intensity, is impossible. 
But the sensation may persistently return to the 
focus after each ousting, and the results be prac- 
tically the same as if it had occupied the focus con- 
tinuously. In the case of a more complex object, 
as the ink-bottle on your table, you find, as we al- 
ready have noted, your attention shifting from 
feature to feature. 

The strongest determinant of persisting recur- 
rence is emotional coloring. That which you de- 
sire or hate or love, etc., dwells long (with due re- 
gard to the principle of intermittence) in the focus 
of attention. The naturalist may observe for hours 
a certain small animal because he has a strong 
emotional interest in it and in its relation to certain 
other animals. His attention courses rapidly over 
a great many details, and many factors related to it, 
but comes back again and again to the same features. 



324 A SYSTEM OF PSYCHOLOGY 

It may be asked, " Why does not the boy continue 
to attend to his Latin lesson, since he hates it?^^ 
The answer is that he really does not hate it: it has 
not even that vital emotional interest for him. It 
deadens his emotions in so far as he attends to it, 
and, hence, he does not attend, except as far as the 
fear of consequences or desire of reward, or pride, 
or some other emotional state may supply the neces- 
sary coloring. Give the boy something he hates — 
a boy rival, a hysterical teacher — and he will attend 
to that object with ease and persistence. 



CHAPTER XIX 

THE SUBCONSCIOUS 
I. The Lower Limit of Vividness 

A SENSATIONAL object may be reduced enor- 
mously in vividness by the change which we describe 
as passing from the focus into median conscious- 
ness, and yet the intensity of the sensation be little, 
if any, reduced. This fact suggests the question 
how far this reduction of vividness may be carried. 
There are two forms of this question: (1) May a 
sensation of zero vividness exist? A sensation of 
zero vividness would be one of which no person is 
conscious at all. This question is strictly meta- 
physical, and although it is possibly the most 
fundamental of all the questions concerning con- 
sciousness, we cannot consider it here. (2) May 
a sensation be so reduced in vividness that analytic 
consciousness of it is impossible? An affirmative 
answer to this question would involve the admission 
that there might be consciousness of the given sen- 
sation in a complex of which it is a part, although 

the sensation is not capable of being singled out 

325 



326 A SYSTEM OF PSYCHOLOGY 

therefrom. There can be no doubt as to the ex- 
istence of sensational objects in this condition, and 
it is to this condition that the term "subconscious'^ 
is properly applied. The term " subconscious'' has 
been much misused of late by quasi-psychologists 
and by physicians, and it has been made to cover 
a multitude of bizarre and absurd theories; hence, 
the conception of a psychological subconsciousness 
needs our careful consideration. 

2. What the Subconscious is Not 

Popular writers tend to confuse the subconscious 
with the conditions of automatic and reflex move- 
ments. Because a complex action, such as walk- 
ing or knitting, is learned through consciousness 
of the details of the action, and is later performed 
without consciousness of these details, the details, 
it is said, have been turned over to the "subcon- 
scious." Of course this is true if by subconscious- 
ness we mean simply that which is below the level 
of consciousness, and certainly these details are 
taken care of by physiological mechanisms which 
do not require consciousness to direct them. The 
authors to whom we refer really mean more than 
this, and conceive of a lower level of consciousness 
attending to the whole mass of such automatic ac- 



THE SUBCONSCIOUS 327 

tions. There have not been lacking enthusiasts 
who have considered digestive functions and the 
growing of the nails as supervised by this subsidiary 
consciousness. 

Another misuse of the concept of subconscious- 
ness is to consider it as the repository of forgotten 
ideas. The remarkable fact that something which 
has not returned to consciousness for a long time — 
some incident of childhood, for example — may at 
any time come back, has led the wilder theorizers 
to suppose that all content is contained in the 
" mind'' in very much the same form in which it was 
originally in consciousness. The normal conscious- 
ness, they say, includes but a small part of the total 
field. The vast remainder is in subconsciousness. 
Recollection is, accordingly, only the movement of 
an idea from subconsciousness into consciousness. 
The idea existed in your mind during the interval 
when it was forgotten. 

It is absolutely necessary for the student to rid 
himself of all such fantastical notions. Content 
forgotten is in general not in any sort of conscious- 
ness, although it may have its effects in present 
consciousness. The learning of motor-adjustments 
is the process of turning those adjustments over to 
mechanisms which need no conscious supervision. 



328 A SYSTEM OF PSYCHOLOGY 

3. The Two Sorts of Marginal Consciousness 
As I sit here writing I do not consciously hear the 
ticking of the clock. Yet, if the clock should stop 
I would be aware of the stopping. I may be so 
absorbed in my task that if the clock strikes I do 
not notice it at the time. But several minutes later 
I may recall the striking and in memory count the 
strokes. 

We are constantly subjected to stimuli of all sorts 
which give rise to sensations, but these sensations 
do not rise to any considerable degree of vividness. 
In the vast majority of cases these sensations and 
sensation-complexes cannot be recalled or remem- 
bered unless unusual means are employed. Nor- 
mal recall, as we have explained, depends princi- 
pally on association, and association depends on 
vividness. Various means for the recall of what 
was perceived marginally or subconsciously may 
be employed. For example, the subject may be 
hypnotized, and, when questioned in that state, may 
give evidence of the recall of percepts which he 
did not notice at all. The subconscious percepts 
may be obtained, in the first place, by calling his 
attention strongly to some visual object to which 
he turns the line of regard, and simultaneously 



THE SUBCONSCIOUS 329 

displaying some object in peripheral vision. In 
the hypnotic state the subject may describe the 
object which he did not know that he saw. The 
theorists have explained this by saying that by 
hypnosis the subconscious part of the mind is made 
conscious. This really amounts to saying that we 
don't know as yet how the phenomena are pro- 
duced. The recall of subconsciously perceived ob- 
jects may occur in a reverie or in the pathological 
state of "crystal gazing.^' In the latter state the 
subject, thrown into a state of light hypnosis by 
gazing fixedly into a crystal sphere or a bowl of 
water held close to the eyes, obtains visual hallu- 
cinations in which former percepts, subconsciously 
perceived, appear. Another aid to the recall of 
subconsciously perceived objects consists in show- 
ing the subject a part of the former object, which 
may recall the remainder of the details, since asso- 
ciation of a certain strength is established even at 
the low vividness of the subconsciously perceived 
object. 

In none of these cases is it necessary to assume 
a subdepartment of consciousness in which the per- 
cepts are held over between the original perception 
and the recall. The contents are perceived, dis- 
appear, and are recalled just like any percepts, ex- 



330 A SYSTEM OF PSYCHOLOGY 

cept for the fact that the low vividness of the per- 
ception makes recall difficult. 

The effect of the subconscious perception may 
be demonstrated, even when recall is impossible. 
If you present to a subject a number of cards con- 
taining simple marks or designs, some of which he 
has previously seen subconsciously, and if you ask 
him to choose several from the number, he will be 
apt to choose the ones which were previously seen. 
The above are typical experimental procedures for 
demonstrating the existence of subconscious per- 
ception. 

The second sort of marginal consciousness is 
rather hypothetical. If it exists, it is the content 
produced by stimulation which is so low in intensity 
that it cannot be vivid even under the best normal 
conditions. A sound, for instance, may be so 
weak physically that it cannot be perceived, al- 
though the air-waves are actually causing nerve- 
excitation in the ear. This is shown by the fact 
that the sudden stoppage of a very weak (physical) 
tone may be clearly perceived, even though the tone 
itself may have been imperceptible. It may be 
said that the tone was in marginal consciousness, or 
subconsciousness, and this view is supported by 
the introspection of the persons taking part in such 



THE SUBCONSCIOUS 331 

experiments. What is heard at the moment of the 
interruption of a stimulus is described as the cessa- 
tion of a tone, and not simply some disturbance 
which might be taken to mean the cutting off of 
the stimulus. The interpretation of these phenom- 
ena and similar phenomena in other sense-realms 
is beset with difficulties; neither the arguments for 
the subconscious explanation nor the objections to 
it are very weighty. Hence, the matter is best re- 
garded as a problem for experimentation rather 
than for theorizing. 

4. Multiple Personality 

The strongest impulse to postulate a subcon- 
sciousness of the sort we are unwilling to admit 
comes from certain phenomena of abnormal psy- 
chology which are known as "alternations of per- 
sonality" or " multiple personality." In some cases 
a patient may suddenly forget the events of his past 
life and lose the habits and traits of character 
which previously have distinguished him. He be- 
comes by this rapid transformation a man of an 
entirely different sort; he may call himself by an- 
other name; we may say he has a new personality. 
The patient may continue for months in his new 
life, and then suddenly his former memories may 



332 A SYSTEM OF PSYCHOLOGY 

return, and with their return the memory of the 
intervening months be lost. He returns to the first 
personality and knows nothing of the second. 
After a longer or shorter time the patient may re- 
lapse into the second personality, remember now 
all that occurred when he had this personality, and 
forget both periods of the first. The two person- 
alities may continue to alternate, or, in other words, 
the person may continue to alternate between the 
two conditions. There may be three or more dis- 
tinct personalities involved and the conditions in 
regard to memory may be much more complicated 
than in the case which we have just described. The 
patient, for example, when he has personality No. 1 
may know^ nothing of what has occurred when he 
had either of the other personalities. But when he 
has personality No. 3 he may remember perfectly 
all that happened while he was in the other two 
states. He may insist that the experiences in states 
1 and 2 were not his experiences, but were the ex- 
periences of some other person. 

If we conclude, as some psychologists have done, 
that the different abnormal personalities exist simul- 
taneously, and that sometimes one, sometimes an- 
other, gets the upper hand, forcing the experiences, 
memories, and processes forming the others out of 



THE SUBCONSCIOUS 333 

consciousness, either as subconscious or co-con- 
scious states, the statement of the case from the 
point of view of pathology and therapeutics is 
simple. The personality of the individual appar- 
ently has lost its organic unity, and has fallen 
into two or more fragments which are loosely con- 
nected with each other. If by the use of proper 
means (as, e. g,, hypnosis) the fragments of the per- 
sonality are reunited, the patient is cured. But 
the hypothesis of co-consciousness gives us no real 
information as to the actual significance of the 
patient's symptoms, nor as to the actual processes 
involved in the removal of the symptoms. 

The acceptance of the subconscious or co-con- 
scious explanation of alternating personality would 
logically involve the acceptance of the same expla- 
nation for the forgotten ideas of normal life. On 
the other hand, we can state the facts of the aberra- 
tions of memory in pathological cases without in- 
volving the hypothesis of the unknown, just as 
easily as we can state the conditions in normal cases. 
In neither the pathological nor the normal cases is 
it necessary to assume that forgotten ideas are car- 
ried along in a co-consciousness during the period 
in which they are not remembered. 

As for the non-ideational factors involved in per- 



334 A SYSTEM OF PSYCHOLOGY 

sonality — habits of action and emotion — the as- 
sumption of a co-consciousness adds nothing to the 
explanation of their appearance and disappearance. 
To say that a man has a certain habit of speech, for 
example, means simply that, as a matter of fact, 
his vocal organs move in a certain way. If the 
vocal organs cease to function in the way indicated, 
and function in a different manner, the habit has 
become non-existent. It cannot coexist with the 
new habit, although the nervous mechanism may 
not be so completely modified that it will not event- 
ually return to its earlier condition and reinstate 
the old habit. 

It is true that a large part of habit is ideational; 
the bodily functions are influenced by the processes 
in representative consciousness. But an emphasis 
on this aspect of habit simply brings us back to 
the first problem: how to account for the ideas 
which were in consciousness and may be in con- 
sciousness again, but are out of consciousness at 
present. 

We are justified in concluding that the assumption 
of a detached subconsciousness or co-consciousness 
to explain the phenomena of alternating person- 
ality is not at present defensible, since the idea- 
tional problems involved in these phenomena are 



THE SUBCONSCIOUS 335 

quite like those involved in all mental life, and the 
problems of neural disposition and modification are 
not affected in any way by the hypothesis of co- 
consciousness. 



CHAPTER XX 

THE EGO 

Experience cannot be completely accounted 
for in terms of bare consciousness and the content 
alone. Experience of any content intrinsically 
implies something experiencing that content. The 
immediate fact of one^s own consciousness is always 
something which may be expressed by the words, 
" I perceive," " I feel," " I imagine," etc. The " I," 
or real Ego, which is the essential centre of reference 
for the whole of the content of consciousness, is not 
itself a fact of content, and hence is not a feature of 
psychological analysis: it is the one thing which, 
as the subject, stands over against the whole of 
objectivity, and hence, while not discovered by any 
analysis, it is involved, not only in every attempt at 
analysis, but in every bit of experience. 

The celebrated formula of Descartes, Je pense, 
done je suis, expresses what is immediately given 
as a fact of experience. Thinking, in the Cartesian 
terminology, is exactly synonymous with beiiig con- 
scious in ours. What Descartes says is that con- 
sciousness is intrinsically something which con- 

336 



THE EGO 337 

cerns an "I'' or "Ego": that there is no such thing 
as impersonal experience. So far we must agree 
with Descartes; but he follows this statement of 
inevitable introspection with the assumption that 
the "I" is a thinking substance^ and in this step we 
cannot follow. 

The '*!'' is not anything which can be defined 
in terms of objectivity — as the metaphysical sub- 
stance is necessarily defined. It is the pure subject, 
which is uniquely and antithetically removed from 
all objectivity, and which is yet involved in all ref- 
erence to objectivity. 

Any attempt at the discussion of the "I" involves 
us in a maze of paradoxes. The "I" cannot be 
discussed, because it is actually non-objective. It 
has no qualities: and yet this very statement is a 
quasi-qualitative ascription. The only unambigu- 
ous statement we can make concerning it is that " I 
experience" or "I am conscious." 

There is a method of explaining away the "I" 
sometimes adopted by psychologists, which consists 
in assuming that content experiences itself. Thus, 
one "state of consciousness" (using this term as 
synonymous with the term "content") is assumed 
to experience the state w^hich just precedes it in 
time: or, one group of content factors is assumed 



338 A SYSTEM OF PSYCHOLOGY 

to experience the remainder of the factors in any 
given content. The subject, in accordance with 
this theory, is identified with one portion of the 
content, and the other portions of content are de- 
scribed as the apprehended objects. There are 
several other forms of the content-subject hypoth- 
esis. One form of the hypothesis does not sup- 
pose a definite part of the content functioning at a 
given time as the subject, but simply assumes in a 
more vague way that the varying details of the con- 
tent which is present at a given moment are present 
by virtue of being in a definite sort of mutual re- 
lationship. This relationship constitutes at once 
the consciousness and subjectivity: it is subjectivity 
without a subject. 

These views assume at once more and less than 
experience gives us. They assume, in the first place, 
a relationship in content which we cannot find there. 
That I experience a certain red may be defined as 
a relation between red and the other factors of con- 
tent, and we do actually experience relations in this 
connection; but the relations we find in the con- 
tent are all relations which determine the red as it 
is experienced, and are none of them, severally or 
together, identifiable as the experience. On the 
other hand, these theories simply ignore the fact 



THE EGO 339 

that in searching the content for any sort of relations 
we are assuming a point of view totally outside the 
content from which to make the inspection. This 
omission is much the same as that which is made by 
those philosophers who claim that the universe is 
just one substance, which, looked at in one way is 
called matter, and looked at in another way is 
called mind. They fail to see that the point of view 
from which the one substance is looked at, now this 
way and now that, is something assumed in addi- 
tion to the one substance; if substance is strictly 
one, and if there is nothing else, it can look at itself 
from only its own single point of view. When we 
try to make consciousness depend on content alone 
we are neglecting the fact that we are now repre- 
senting consciousness from an outside point of view 
and have not given a fair account of conscious- 
ness till we indicate how we got to this point. If 
we represent this consciousness in any sort of sym- 
bolic way, as we may represent content, it is ijpso 
facto not adequate, because we still are assuming 
a consciousness of the symbolization without which 
it is impossible. 

We are obliged to assume, then, a point of view 
or point of reference over against content; perhaps 
the '* transcendental unity of apperception" of 



340 A SYSTEM OF PSYCHOLOGY 

Kant; and it is just the orientation to this point of 
view which constitutes consciousness. It, of course, 
cannot be symbolized or described, because as soon 
as it is described it becomes no longer the point of 
view to which the consciousness refers. 

We speak of this transcendental point of view as 
" I/^ The " I,'* if we accept the fact of it, must not 
be supposed to be active. Activity of any sort is 
an objective fact and is in the objective world. 
The "I" is the pure subject and is incapable of 
anything except being a subject. 

It may be asked, of what use is it to suppose the 
^*I," which has no qualities, cannot be analyzed or 
scrutinized, and can do nothing; and, also, if it is 
not describable or scrutinizable, how can we know 
it is there. The answer to both questions is, that 
the "I^* is of no use, but that our analysis of the 
content of consciousness presupposes it, and hence 
we admit it. We do not observe the Ego, but it 
is involved essentially in every observation. It is 
really the only thing that observes or is conscious : 
hence, it has immediate claim to existence. 

The view outlined above is believed to be that 
from which a satisfactory and adequate account 
of consciousness can be given. It is a view which 
is much older than modern civilization, but fits 



THE EGO 341 

in as acceptably with scientific psychology as with 
ancient philosophy and religion. It is the only view 
which completely justifies the universal practice of 
modern psychology in leaving the " I/' or Ego, out 
of its analysis; for if the Ego were not transcen- 
dental it would have to be treated analytically in 
psychology, instead of being merely assumed. Be- 
ing transcendental, the Ego has practically no in- 
terest for psychology or science. 

Modern psychology is truly said to be psychology 
without a soul, but if the transcendental point of 
reference or subject is what is meant by the term 
soul, psychology not only does not deny the soul, 
but positively aflSrms it. We must, however, bear 
in mind the fact not only that we can know nothing 
about the Ego, but that there is nothing to be known 
about it. 



CHAPTER XXI 

THE OCCULT 
I. The Study of the Occult 

In discussing the transcendental Ego we were 
upon dangerous ground. So much bias exists 
among those persons whose fields run into that of 
psychology that it is impossible to make any state- 
ment, however judicious, concerning the Ego with- 
out incurring the antagonism or contempt of some 
of these individuals. The same conditions sur- 
round us in the discussion of the occult. It is quite 
noticeable that writers who have expressed opinions 
on this subject have met with a great deal more than 
intellectual dissent from their opinions. Especially 
unpleasant has been the position of those who 
have agreed with none of the extreme views on 
psychic research, and in consequence have been 
denounced from all sides. This explanation is 
necessary in order that the student may know that 
what is set down in this chapter is not apt to be 

approved by even a considerable minority of rep- 

342 



THE OCCULT 343 

utable scientists, to say nothing of the vast com- 
pany of fanatics. 

Just what is here meant by the occult, the reader 
will gather as he proceeds. The things treated 
under this heading are properly the subject-matter 
of what is called psychic research, but in one way 
or another are also interesting and important for 
psychology. Psychic research is at present in dis- 
repute among scholars, largely because psychic re- 
searchers do not take a logical psychological attitude 
toward the phenomena they investigate. Psychic 
research, the investigation of phenomena which are 
alleged to be not in accordance with accepted views 
of natural law, is a perfectly legitimate activity. Its 
purpose is two-fold: first, to accumulate data for 
psychological study; and second, to rout rascals and 
to dispel popular superstition. 

2. Telepathy 

It is popularly believed that the thoughts of one 
person may directly influence those of another. 
This belief is somewhat akin to the ancient super- 
stition that the eye of one person is able to affect 
another person. Vision is sometimes called touch 
at a distance, and it is hard for the savage (and 



344 A SYSTEM OF PSYCHOLOGY 

philosophical savages are still extant) to believe 
that when his eye rests upon another person or ob- 
ject something does not go out from his visual 
organ to take in the percept of the other, much as 
his finger would be stretched out to get a tactual im- 
pression. From this naive conception of the phys- 
ics of vision the belief in the evil eye probably 
arises, and from it comes also the harmless super- 
stition of the present day, that one person can attract 
the attention of another by gazing intently at the 
back of his head. It is possible that the fully de- 
veloped eye-power superstition involves the alleged 
phenomena or thought-transference, as well as 
the supposed power of the eye itself. Telepathy, 
which is believed in by many persons at the present 
time, is the (alleged) effect produced on the con- 
sciousness of one person by the mental operations 
of another. 

As a matter of fact, we have been able to discover 
no communication between persons except that 
which takes place through what we call the physical 
world. I may have the sensation which you have 
if I am subjected to the same stimulus. I may 
think of the object of which you are thinking if 
some common perception is associated with the 
object in each of us. By a perfectly definite chain 



THE OCCULT 345 

of association two or more persons often arrive with 
approximate simultaneity at the thought of some- 
thing which has not been directly mentioned. If, 
however, one person thinks of a certain object 
because another thinks thereof, the thought of the 
second person must have expressed itself in some 
objective sign which was perceived by the first per- 
son, and which aroused the thought of the given ob- 
ject by normal association. 

Certain interesting phenomena which are com- 
monly designated by the term ^* mind-reading^' 
offer confirmation of this conclusion. Mind-read- 
ing is frequently undertaken as a parlor amuse- 
ment, and some of the most striking results are ob- 
tained by amateurs. A subject may be sent from 
the room while the remainder of the company de- 
cide on some act he is to perform on returning. 
The subject is brought in by two of the company 
acting as guides, usually with their hands on the 
shoulders of the subject. All the company think 
intensely of the appointed action, and the subject in 
many cases proceeds to perform it, after more or 
less delay. 

Variations may be introduced into such an ex- 
periment which prove that the subject perceives 
(usually marginally) slight pressure sensations from 



346 A SYSTEM OF PSYCHOLOGY 

the hands of the guides, which, by association, bring 
up the idea upon which the designated action fol- 
lows. As might be suspected, the experiment suc- 
ceeds best when the subject is convinced that he is 
receiving mental influence, and fails when he at- 
tempts to interpret pressure sensations consciously. 
Not all persons succeed as subjects; a condition of 
mental equilibrium is required in which slight 
associations may be effective; a condition not easily 
obtained by every one. 

Sometimes the mind-reading succeeds when there 
is no contact between the subject and any one else. 
Such cases are very few, the professional demon- 
strations being pure humbug. In the few cases 
that are genuine, the subject is able to interpret 
changes in the breathing of the company as signs 
that he is starting to do the right or wTong thing, or 
else is guided by faint sounds made by the vocal 
organs of those thinking of what he is to do. The 
majority of adults partially articulate words in 
thinking, and this slight vocal action occasions air- 
waves which may affect the ears of the subject, and 
thus produce the effects subconsciously. If the 
subject be blindfolded and have the ears stopped 
(a diflBcult condition to obtain, by the way), mind- 
reading without contact will in no case succeed. 



THE OCCULT 347 

There is a wide-spread belief that in hypnosis the 
patient is responsive to the thoughts of the hypno- 
tizer. The phenomena of hypnotism are some- 
times described in terms of the influence of one 
mind on another, but this influence is always pro- 
duced in the normal way — by physical signs. The 
hypnotizer may think as much and as intensely as 
he pleases, and the patient will not fathom his inten- 
tion unless he gains some inkling of the thought by 
visual, auditory, or other sensations. In certain 
cases the hypnotized patient may interpret signs 
more readily than does the normal subject, but such 
is not always the case. The exact nature of the 
hypnotic state is not yet clearly understood. The 
ideas suggested by the hypnotizer occupy the pa- 
tient's mind, driving out any which are conceptually 
incompatible with them, and, if they are ideas of 
action, the actions follow mechanically according to 
what we would expect under the principle of ideo- 
motor activity when all checks and inhibitions are 
removed. This description of the hypnotic state 
does not explain it. 



348 A SYSTEM OF PSYCHOLOGY 

3. Mysticism 

Closely related to the theory of telepathy is the 
doctrine of mystic knowledge. This doctrine, which 
is found in the writings of many modern men of 
letters, comes to us directly from the Neoplatonic 
philosophy of the so-called Alexandrian school. 
The writings formerly ascribed to Dionysius the 
Areopagite, but now admitted to belong to the 
fifth century, embody the Neoplatonic doctrine 
in its characteristic form; and these writings, trans- 
lated and studied by the scholastic philosophers, 
have been the direct sources of mediaeval and mod- 
ern mystical beliefs. 

In brief, mystic knowledge is supposed to be a 
form of cognition absolutely different in character 
from sense perception and intellectual apprehen- 
sion, and vastly superior to these. In ecstasy, which 
is the technical name for the act or state of mystical 
knowledge, the subject is alleged to be in direct 
contact with some form of ultimate reality. In 
Maeterlinck^s system, this ultimate reality, which the 
soul is supposed to know or experience in this mystic 
way, may be another soul: in the original system, 
and the system of certain other modern mystics, 
the reality which is experienced is the Divine Being. 



THE OCCULT 349 

The nature of this mystic knowledge is, according 
to the theory, indescribable, because it is entirely 
removed from the sphere of ordinary knowledge, in 
which sphere only are descriptions and explanations 
possible. The statement which comes nearest to 
the mystic's doctrine, is that in ecstasy the soul is 
united w^ith God ( or with another soul). 

The mystic experience must be carefully dis- 
tinguished from the seeing of visions or the hearing 
of voices (as in the case of Joan of Arc), and from 
the " feeling of the presence'' of some one — a feeling 
in which many people believe. The mystic experi- 
ence is not at all the acquirement of the ordinary 
form of knowledge in a mysterious way: it is an ex- 
traordinary form of knowledge. The experiences 
which approach this condition, but which remain 
in the ordinary sphere, may be conveniently desig- 
nated as pseudo-mystical. 

With the claims of mysticism psychology has 
strictly nothing to do. When some one tells me 
that he has had a kind of experience which has 
absolutely no relation to my experience, I have 
as little ground for admitting the truth of his state- 
ment as for denying it. Nevertheless, when the ex- 
perience of another person can be satisfactorily 
explained in terms of our own experiences, we must 



350 A SYSTEM OF PSYCHOLOGY 

provisionally explain it in that way. The mystic 
distinctly tells us that in ecstasy there is conscious- 
ness — but no perception or imagination or intellec- 
tual process. From which we conclude that the 
experience — if it really occurs — is of pure feeling. 
This conclusion we believe to be satisfactory and 
final. 

4. Spiritualism and Mediumship 

A large and varied assortment of performances 
and superstitions have come to be included under 
the name of spiritualism or mediumship. Me- 
diums, or "psychics/' or clairvoyants, pretend to 
produce table-tipping, slate-writing, playing on 
musical instruments, and other physical phenomena 
without ordinary physical means. They read the 
future and the past, and put you in communication 
with Julius Csesar, or Flashing-Eyes the Indian 
maiden, or your great-grandfather. A few words 
about these performances are appropriate here. 

In the first place, supernatural mediumships — 
the production of physical effects without adequate 
physical causes — must be excluded from the dis- 
cussion. The table-tippings, slate- writing, "spirit- 
photographs, " and other tricks have been explained 
and exposed until they have become merely a 



THE OCCULT 351 

source of weariness. Every supernatural medium 
who has been carefully investigated has been found 
to be a fraud. All the tricks of the psychics have 
been done by Kellar and the stage magicians, and 
many of the performances of these men have defied 
the investigation of scientists, until the magicians 
themselves have furnished the explanations. 

The production on slates or other surfaces of 
writing or pictures which are claimed not to have 
been produced by natural hands and processes, is 
conclusive proof of fraud. When a medium causes 
a table to tip or rise into the air, apparently without 
physical aid or support, or causes voices to sound or 
instruments to play, which voices and which play- 
ing are claimed not to be the medium's or her as- 
sistants', she brands herself as a humbug. The 
materialization of a spirit is convincing evidence 
that the medium presumes on the crassest credulity 
on the part of her patrons. 

In other cases, the mediums are possibly honest. 
Psychic healers who claim to heal broken bones or 
bacterial diseases by mental treatment, sometimes 
when the patient does not know that he is being 
treated, may think they can perform these miracles. 
People have always believed in witchcraft and 
sorcery, and the sorcerers themselves, whether voo- 



352 A SYSTEM OF PSYCHOLOGY 

doo doctors or "Christian Science" practitioners, 
are usually ignorant enough to share the belief. On 
the other hand, the psychic treatment of nervous 
disorders is an established and valuable method, 
the "mental'^ state of the patient having a profound 
effect on his "bodily" functions. Psychotherapy is 
employed by scientific physicians, and it may often 
be employed by the most ignorant sort of charlatans 
with great success. If the patient thinks that he is 
receiving treatment and is being benefited, the 
benefit frequently follows. 

Psychic treatment cannot take the place of other 
sorts of medical treatment where these are indicated. 
In diseases of other than nervous origin the patient's 
state of mind is important, but its importance is 
relatively small. Many patients, of course, get well 
without medical attention — physicians do not claim 
to "cure" any disease, but simply to assist nature 
in its fight against it — and many cases occur in 
which the patient thinks he has a disease from which 
he is really free, and, upon feeling better, he may be 
of the opinion that he has been cured of that disease. 
Hundreds of cases of cures by " Christian Science," 
which are described as having been cured after the 
patients had been given up by the doctors to die of 
a disease, have been investigated, and in not one 



THE OCCULT 353 

case out of fifty has it been found that such a diag- 
nosis had actually been made. 

In natural mediumships there is no pretence of 
effects produced in a supernatural way. If writing 
and other phenomena are produced, they are the 
work of the medium, and no claim is made to the 
contrary. The only question at issue is as to the sig- 
nificance of what is written or spoken by the medium. 

The natural mediums usually claim that what 
they have to communicate comes from the "spirits" 
— a "spirit" takes control of the hand or the vocal 
organs of a medium and expresses itself by means 
of them. This hypothesis would explain some of 
the remarkable things which have been " communi- 
cated" by certain mediums, if it were not for the 
fact that we don't really know what we mean by the 
term "spirit." The "spirits" would seem to be 
decaying fragments of former personalities, since 
their communications are usually trivial, and mixed 
with much pure rubbish. For the present it is 
safest not to adopt any hypothesis whatsoever for 
the explanation of natural mediumship, but to hold 
the few remarkable results of experiments with 
mediums as interesting data requiring much to be 
added before any explanation can be attempted. 
It is by no means impossible that it may all be ex- 



354 A SYSTEM OF PSYCHOLOGY 

plicable as chance and cheating. The societies 
for psychic research have for a long time been en- 
gaged in investigating all cases of mediumship which 
seem geniune, but have received little recompense 
for their labors. Certainly they have learned noth- 
ing about the future life — the existence of persons 
after what we call death. 

It is to be noted that the natural mediums who 
have seemed genuine can be counted on the fingers. 
By genuine is here meant that they are not con- 
sciously trying to deceive: that the information they 
furnish comes from a source unknown to themselves. 
The large body of professional clairvoyants, sooth- 
sayers, and psychics is simply a group of impostors. 



REFERENCES 

The student is urged to compare the view-points and 
interpretations of the foregoing treatise with those of 
other texts. The most important shorter treatises are : 
Ward, article, "Psychology/' in the Encyclopaedia Bri- 
tannica, eleventh edition; Angell, Psychology; Titchener, 
Text-Book of Psychology; Kiilpe, Outlines of Psychol- 
ogy, and Maher, Psychology, The important longer 
ones are: Ladd and Woodworth, Elements of Physio- 
logical Psychology; Wundt, Grundziige der physio- 
logischen Psychologic; Ebbinghaus, Grundziige der Psy- 
chologic, and James, Principles of Psychology. The 
last named is the most important of all in point of theory. 

As a manual for the further study of the data of psy- 
chology Ladd and Woodworth's book is especially to 
be recommended. Recent books and articles on any 
topic may be located by consulting the Psychological 
Index, which is issued annually by the Psychological 
Review, and contains all the titles for the year on psy- 
chology, philosophy, and the relevant parts of neurology 
and physiology. 

Below are given a few references on points which are 
emphasized in the foregoing treatise, some of the articles 
being in agreement with our positions and some not. 

On the Greek theory of the psyche: Turner, "Aris- 
totle as a Psychologist," Catholic University Bulletin, 
XVII, 299-317; Aristotle, De Anima (in Hammond's 
Aristotle's Psychology), especially books I and II. 

355 



356 REFERENCES 

On the original use of the term psychology: Hamil- 
ton, Lectures on Metaphysics, Lecture VIII. The defi- 
nitions of the present science of psychology given in stan- 
dard treatises do not differ much from the definition we 
have given in chap. I, § 1. Stout, Manual of Psychol- 
ogy, Introduction, chap. I, § 1, gives a definition which 
is somewhat broader and possibly more accurate. The 
definition given by Pillsbury, Essentials of Psychology, 
does differ essentially from the orthodox one, and might 
be made the basis of a distinct sort of psychology. Pills- 
bury, however, virtually abandons his definition, ^nd 
follows rather conventional lines. Kirkpatrick, Genetic 
Psychology, approximates more nearly to a ^'behavior" 
psychology. 

On the restricted meaning of consciousness: Ham- 
ilton, "Philosophy of Perception," in Discourses on Phi- 
losophy and Literature, See also Mill, Examination of 
Hamilton's Philosophy, chap. VIII. For a modern dis- 
cussion of consciousness, see Hicks, "The Relation of 
Subject and Object," Proceedings Aristotelian Society, 
VIII (1908), 161-214. For a purely functional theory of 
consciousness, see James, "Does Consciousness Exist?" 
Journal of Philosophy, etc., I, 477-491. The title of 
this article is, of course, not to be taken literally, but is 
to be understood as questioning the validity of a certain 
theory concerning consciousness. 

On ELEMENTS of Content: Watt, "The Elements of 
Experience," British Journal of Psychology, IV, 127- 
204. 

On the identification of sensation and brain proc- 
ess: Loeb, Comparative Physiology of the Brain, chaps. 
I, XV-XVIII, and especially IX; Forel, Nervous and 



REFERENCES 357 

Mental Hygiene, chap. II; Pearson, The Grammar of 
Science, chap. II, § 4. Many physiologists who prac- 
tically adopt this view do not formulate it definitely. 
Certain physiologists explicitly reject the theory: see 
Howell, Physiology, pp. 182, 183. Certain others grope 
in utter confusion, making absolutely no distinction be- 
tween consciousness and object, or between matter and 
either of these; see McNamara, The Evolution and 
Function of Living Purposive Matter, in which the 
paragraph in the middle of page 148 is typical of the 
whole book. 

For a clear statement of the parallel theory and 
the arguments for it, see Mercer, Sanity and Insanity, 
chap. III. An instance of the difficulty found by even 
the best intentioned parallelists in actually maintaining 
a position on the theory may be observed by attempt- 
ing to interpret the section headed. The Appearance of 
Consciousness, in chap. Ill of Angell's Psychology, in 
the light of the statements made in the section headed 
Terminology, in the same chapter. 

For a statement of the interaction theory, see Ladd 
and Woodworth, Elements, pt. III. James's Principles 
is based on the interaction theory. 

For Huxley's theory of the nature of matter, see 
his essay on ^^The Physical Basis of Life," particularly 
the latter portion thereof. On this problem, see also 
Mill, Examination of Hamilton's Philosophy, chap. XI. 

For the telephone theory of audition, see Ruther- 
ford, ''The Sense of Hearing," Lancet, 1887, I, 2-6. 
On the extensity theory: Ter Kuile, Pflilger's Archiv, 
LXXIX, 146-157, 484-509; Dunlap, "Extensity and 
Pitch," Psychological Review, XII, 287-292. 



358 REFERENCES 

On MUSICAL scales: Ellis's translation of Helmholtz's 
Sensations of Tone; Sabine, ^'Melody and the Origin of 
the Musical Scale," Science^ N. S. XXVII, 841-847. 
Naumann, History of Music (Praeger's translation). 

On VISUAL SENSATION in general, the articles by Nagel 
and by Von Kries in Nagel, Handbuch der Physiologie, 
are especially to be recommended. See also Green- 
wood, ^^Studies in Special Sense Physiology," in Hill, 
Further Advances in Physiology (1909). On the 
STREAMING PHENOMENA, scc Wohlgemuth, '* On the 
After-Effect of Seen Movement," British Journal of 
Psychology, Monograph Supplement No. 1. 

On the variability of the temperature spots: Craw- 
ford, "A Study of the Temperature Sense," Psycho- 
logical Review, V, 63-112; Kelchner and Rosenblum, 
Zeitschrift fur Psychologic, XXI, 174-182. 

On the DISSOCIATION of dermal sensation qualities 
by syringomyelia and other nervous diseases: Starr, 
Organic and Functional Nervous Diseases. 

On RELATIONS AS ELEMENTS OF CONTENT: Huxlcy, 

Essay on Hume, chap. II; Woodworth, "The Conscious- 
ness of Relation," Essays Philosophical and Psychological 
in Honor of William James, 485-507; McGilvary, "The 
* Fringe' of Wilham James's Psychology," Philosophical 
Review, XX, 137-164. An interesting attempt at the 
analysis of relations is contained in Spencer, Principles 
of Psychology, second edition, II, chaps. XV-XXVI. 
See also Brunschwig, Das Vergleichen und die Relation- 
erkenntniss. The specific question as to the existence of 
relation content is involved in the less sharply defined 
question whether or not "imageless thought" exists, and 
the two are sometimes confused. On imageless thought. 



REFERENCES 359 

see Titchener, Lectures on the Experimental Psychology 
of the Thought Processes, 

On IMAGES AND IDEAS : Aristotle, De Anima, book III, 
chaps. Ill and VII, On Memory and Recollection, and 
On Dreams (in Hammond, Aristotle's Psychology); 
Hamilton, Philosophy of Perception, foot-note on the his- 
tory of the term idea; Alexander, "On Sensations and 
Images," Proceedings Aristotelian Society, X (1909), 1-35; 
Colvin, "The Nature of the Mental Image," Psycho- 
logical Review, XV, 158-169; Angell, "Methods for the 
Determination of Mental Imagery," Psychological Re- 
vieWy Monograph Supplements, XIII (1), 60-108; Stout, 
Manual of Psychology, book IV, chap. I. 

On CONCEPT AND JUDGMENT: Mill, Examination of 
Hamilton's Philosophy, chaps. XVII and XVIII. 

On the PLATONIC "idea": Plato (Jowett's transla- 
tion), Parmenides, 132, Phcedo, 100-106, Republic, book 
VI, and especially book X, 596-598. (The numbers 
are those in the margins.). 

On association: Claparede, U association des idees, 
and Calkins, "Association," Psychological Review, 
Monograph Supplements, I, (2). 

On space perception: Wundt, Physiologische Psy- 
chohgie, sixth edition, II, cap. 13, § 5 and cap. 14, § 6; 
Ribot, German Psychology of To-day, chap. IV; Sully, 
The Human Mind, II, Appendices B and E; Kolben- 
heyer, Die Sensorielle Theorie der optische Raumem- 
pfindung ; Von Aster, "Beitrage zur Psychologic der 
Raumwahrnehmung," Zeitschrift fiir Psychologic, 
XLIII, 161-203. 

On time perception: Montague,. "A Theory of Time 
Verception,'' American Journal of Psychology , XV, 1-13; 



360 REFERENCES 

Nichols, "ThejPsychology of Time/' same Journal, III, 
453-527. Hamlin, " On the Least Observable Interval,'' 
etc., same Journal, IV, 564-575. 

On the question whether feeling is sensation or is sui 
generis, and on the degrees of consciousness: Titch- 
ener. Lectures on the Elementary Psychology of Feeling 
and Attention, On the James-Lange theory of the emo- 
tions, see James's defence, "The Physical Basis of the 
Emotions," Psychological Review, I, 517-529. 

On rhythm: Bolton, "Rhythm,'' American Journal of 
Psychology, VI, 145-238; Stetson, "A Motor Theory of 
Rhythm," Psychological Review, XII, 250-270, 293-350; 
Dunlap, "Rhythm and the Specious Present," Journal 
of Philosophy, etc., VIII, 348-354. 

On the subconscious: Hart, "The Concept of the 
Subconscious," Journal of Abnormal Psychology, IV, 
351-371, gives an excellent outline of the theory we re- 
ject; Jastrow, The Subconscious, presents implicitly a 
theory which is even more extreme. 

On ALTERATIONS OF PERSONALITY and multiple per- 
sonality: Prince, The Dissociation of a Personality, pre- 
sents an extreme view strikingly, and illustrates the fact 
that a difBcult problem may be literally dramatized to 
an apparently simple solution. Other standard books 
are: Azam, Hypnotisme et double conscience, and Binet, 
The Alterations of Personality, See also, in this connec- 
tion, Janet, The Mental State of Hystericals, and The 
Major Symptoms of Hysteria. 

On the OCCULT in general, Lang, Psychic Research, in 
the Encyclopaedia Britannica; and Moll, Hypnotism 
(EngUsh from fourth edition, 1910), chap. XIII. On 
MIND READING and telepathy: Moll, op cit., 62, 63, 455- 



REFERENCES 361 

458, 510-519 ; Pf ungst, Clever Hans (Rahn's translation) ; 
Hansen and Lehmann, "Ueber unwilkurliches Fliistern," 
Philosophische Stvdien, XI, 471-530. Curtis, *' Auto- 
matic Movements of the Larynx," American Journal of 
Psychology, XI, 237-239. Laurent, ^*Les procedes des 
liseurs de pensees," Journal de Psychologic, II, 481-495. 

On mysticism: Underbill, Mysticism, gives the best 
presentation from the mystic's point of view. Jones, 
Studies in Mystical Religion, gives an historical account. 
The writings of (the pseudo-) Dionysius the Areopagite 
have been translated by Parker. The writings of Mae- 
terlinck and of Emerson are good instances of the mod- 
ern outcroppings of Neoplatonism which to a large 
extent tincture all theological discourse of the present 
day. See, for example, Maeterlinck, "The Awakening 
of the Soul," and "On Women," in The Treasure of the 
Humble; and Emerson's essay on The Oversold. 

Questions concerning dreams must have been sug- 
gested to the reader by several portions of our book, 
but we have avoided this topic because so little is known 
about it. Interesting speculations and controversies 
concerning dreams are rife at present, but the state- 
ments of these would be too long for this treatise. 
The student may profitably read two books which rep- 
resent the more scholarly attempt to study dreams: 
Mourly Void, Ueber den Traum (Klem, editor), and 
Foucault, La reve. A book which is having a great 
vogue at the present time among medical men, and 
which makes of an arbitrary theory a religious dogma 
rather than a scientific hypothesis, is Freud, Traumdeu- 
tung. See also Jones, "Freud's Theory of Dreams," 
American Journal of Psychology, XXII, 283-308. 



INDEX 



Accent in rhythm, 311 ff. 

Achromopsia, 40, 67 ff. 

Action: 265 ff. ; automatic, 274 ff.; 
and the subconscious, 326; 
habitual, 281 ff. ; ideo-motor, 
267 ff . ; instinctive, 277 ff . , 282 f . ; 
reflex, 254 ff. ; voluntary, 
269 ff. 

Adaptation, protective, 51, 74, 
246. 

iEsthesiometry, 140 f., 217. 

Affective content, 243; and at- 
tention, 323 f. ; in mediate as- 
sociation, 186; and the self, 
287. 

Affective elements, 14, 242; in 
emotion, 15, 255 f. 

After-images; distinguished from 
secondary sensations, 31 f.; 
negative, 76. 

Ageusia, 39, 48. 

Algo-hedonic tone, 263 f. 

Alterations of personality, 291. 

Alternation of personalities, 331 ft'. 

Amblacusia, 144 f. 

Anatomy, 8 ff. 

Anosmia, 39, 46. 

Apperception, 198. 

Appetition, 242 f. 

Apprehension, 16. 

Aristotle's theory of imagination, 
16, 161, 153 ff. 

Art, aim of, 257 f. 

Association; intellectual, 186 f.; 
mediate, 185 f., 190; physio- 
logical basis of, 194 ff.; and 
perception, 209 ff. ; principles 
of, 180 ff.; and recall, 178 f.; 
and retention, 174; strength 
of, 190 ff.; and vividness, 299. 

Associative recall, principle of, 
187 ff. 

Attention, 293 ff.; duration of, 
313 ff., 318, 323 f.; and inter- 
est, 301 f.; and motor adjust- 



ment, 294, 296; scope of, 304 f.; 

in voluntary recall, 193 f. 
Audition, theories of, 81 ff., 123 ff., 

143 f. 
Auditory ossicles, 80. 
Auditory sensations, physical 

conditions of, 80 ff.; pitch of, 

81 ff. 

Beats, 30, 118 f. 

Betweenness, 216, 218, 232. 

Binocular rivalry, 223, 225 f. 

Black, 67; sensational theory of, 
60. 

Blind-spot, 55. 

Brain centres ; auditory, 80; as- 
sociational, 195; of cutaneous 
and sub-cutaneous sensation, 
85 f.; gustatory, 45; of imag- 
ination, 150; olfactory, 50; vis- 
ual, 54. 

Brain-paths, 194. 

Brain processes, actual and ma- 
terial, 21 f. 

Character, personal, 289. 

Characters of sensation, 32 ff. 

Chiaro-oscuro, 223 f. 

Chromopsia, 40. 

Classification of sensation, 38 f. 

Clay's theory of the specious pres- 
ent, 308. 

Clearness, 293. 

Cochlea, 80 ff., 124. 

Co-consciousness, 332 ff. 

Cognition, 242. 

Color adaptation, 74 ff. 

Color blindness, see Achromop- 
sia. 

Color circle, 64. 

Color contrast, 76 f. 

Color mixing by rotating discs, 28. 

Color onion, 65 f . 

Color sensitivity of different por- 
tions of retina, 74. 



363 



364 



INDEX 



Color theories, 59 ft., 70 f., 73, 79. 

Color triangle. 64. 

Colors; complementary, 66; com- 
posite, 57; elementary, 56 ff.; 
fundamental, 57 f. 

Conation, 243; and imagination, 
250. 

Conative feeling; and emotion, 
264; spreading of, 253 ff. 

Concept; and idea, 166 ff. ; in per- 
ceived content, 197 ff.; devel- 
opment of, 198 ff.; and judg- 
ment, 303 ff. 

Confusion, psycho-physiological, 
20. 

Consciousness, 6 f., 292 ff.; de- 
grees of, 293 ff. ; kinds of. 292 f., 
306; span of, 310; time rela- 
tions of, 306 ff. 

Conscious processes, 180, 184 ff. 

Constant errors, 108 ff. 

Content of consciousness, 7 ; com- 
plexity of, 12; elements in, 13 ff.; 
perceived, 196 ff. 

Convergence and accommodation, 
223, 225. 

Corresponding points, 141 ff. 

Cortical centres, 43. 

Dark brown taste, 49, 99. 

Deep sensibility, 93 f. 

Deliberation, 271 f. 

Depth perception, visual, 222 ff. 

Descartes; fundamental formula, 
336; theory of emotions, 259. 

Desire, 242 ff., 250 ff . ; in volition, 
269 ff. 

Despair, 262. 

Determination, 274. 

Dichromopsia, 68. 

Dionysius the Areopagite, influ- 
ence of, 248 ff . 

Direction, spatial, 216, 222 f. 

Distance, spatial, 217. 

Dizziness, 99. 

Duration, 232 ff.; and algo-he- 
donic tone, 246; and proten- 
sity, 35, 120 f. 

Ecstasy, 348. 

Edge-contrast, 77. 

Ego: the empirical, 285 ff.: the 
real, 336 f.; functional theory 
of, 337 ff.; not to be studied, 
337, 339, 341; and will, 271. 



Elements of content, classifica- 
tion, of 13 ff. 

Emotions, 243. 255 ff.; aesthetic 
and religious, 257 ff.; classifi- 
cation of, 263; and coensesthe- 
sis, 259 ff . ; cognitive factors in, 
261 ff.; and feelings, 15; mor- 
bid, 256 f . ; and volition, 270. 

Empiricism, 150. 

Epicritic sensibility, 93 f. 

Error, possibiUty of, 24. 

Evil eye, the, 344. 

Experience, 6; not complex, 12 f.; 
and brain activity, 26 f. 

Extensity, 34, 83 f.; auditory, 
215, 216; differences in, 122 f.; 
and extension, 122, 214 ff.; and 
intensity, 134 ff.; physiologi- 
cal basis, 123; and pitch, 123 ff., 
215 f.; and space, 122. 

Extensity theory of tone percep- 
tion, 83, 123 ff. 

Extension, 214 ff. 

Fechner's colors, 79. 

Fechner's formula, 114 f. 

Fear, 260, 262. 

Feeling, loose use of term, 243. 

Feeling tone, 35. 

Feelings, 243 ff.; as elements, 14 f,; 

and \ividness, 298. 
Fetichism, 252. 
Fiat, 271. 

Field of consciousness, 294. 
Focus of consciousness, 295. 
Fovea, 54. 
Franklin, Mrs.; Color theory of, 

62. 
Fringe of consciousness, 295, 

314 f. 
Fusions, 183. 

Galton's questionary, 153 f. 

Gray sensations, 65 ff . 

Groupings, rhythmic, 309 ff. 

Gustation; physical and physio- 
logical conditions of, 44 ff.; 
confused with olfaction, 45 ff. 

Gustatory papillae, 44, 48. 

Habit, 281 ff.; and alteration of 

personality, 334. 
Hallucination, 203 ff. 
Hedonic tone, 243; and conation, 

250, 255 f . 



INDEX 



365 



Helmholtz; criterion of modality, 
42 f.; theory of tone percep- 
tion, 81, 84, 124, 143 f. 

Hering's color theory, 60. 

Huxley's theory of matter, 26. 

Hypnotism, 268, 347. 

Idealism, 23, 24, 25, 150, 228. 

Ideas, 163 ff.; and algo-hedonic 
feeling, 247 f.; and action, 
267 ff.; and conative feeling, 
251; and volition, 270 ff.; ab- 
stract, 166. 

Ideational reflex, 267 ff. 

Illusion, 201 ft. 

Illusions of reversible perspec- 
tive, 319 ff. 

Images, 14; and ideas, 163 ff., 
167; as copies of sensations, 16; 
spontaneity of, 177 f. 

Imagination, 157 ff.; 306, 307; 
creative, 161 ff.; function of, 
160 ff . ; a kind of consciousness, 
157; perceptional conditions 
of, 169 ff.; physiological proc- 
esses in, 155 f.; reproductive, 
161; in science, 200; and 
scientific training, 165 f . ; types 
of, 154 ff. 

Imitation, 279 f. 

Instinct, 277 f. 

Integration, principle of, 180 ff. 

Intellect, 150 f. 

Intellectual association, principle 
of, 186 f. 

Intensity of sensation, 33, 109 ff.; 
and algo-hedonic feeling, 245 f . ; 
and vividness, 295 ff. 

Interactionism, 22, 25 ff. 

Interest, 242; and apathy, 251; 
and attention, 301 f.; spread- 
ing of, 252 f.; and subjective 
activity, 252. 

Intermittence tones, 30. 

Intuition, 16. 

Irradiation, 135. 

James-Lange theory of the emo- 
tions, 259 ff. 
Judgment, 303 f. 

Knowledge, 7; mystical, 348 ff. 

Learning; accidental, 278 f.; con- 
ceptual, 280 f . ; imitative, 279 f . 



Linnaeus' classification of odors, 
52 f. 

Local sign of sensation, 35, 137 ff. ; 
and complexity of odors, 145; 
differences in, 139 ff.; and ex- 
tension, 139, 216, 222 f.; and 
pitch, 143 ff.; and quality, 138. 

Love, 262 f. 

Margin of consciousness, 228, 295, 
314 f. ; two sorts of, 328 ff. ; and 
mind reading, 345. 

Materialism, 25, 150, 228. 

Matter; not experienced, 19; theo- 
ries of, 26. 

Mediumship, 350 ff.; natural, 
353 f . ; supernatural, 350 ff. 

Memory, 174 ff.; biological and 
psychological, 174 f.; and 
learning, 175 f.; and multiple 
personaUty, 331 f.; and recog- 
nition, 177; and plagiarism, 
176 f. 

Middle term, principle of, 185 f. 

Mind: a multivocal term, 5; as 
brain activity, 22; as objective 
reality, 23. 

Mind-reading, 345 ff. 

Modality of sensation, 42 f. 

Molecular weight and olfactory 
sensation, 19, 53, 101. 

Mood, emotional, 262. 

Motive, 272 f . 

Motor tendency of thought, 284. 

Muscle sensation, 96 f. 

Music and cognition, 258 f. 

Musical ear, 144. 

Mystic knowledge, 348 ff. 

Nausea, 97. 

Neo-Platonism, influence of, 

348 ff. 
Nervous process, ambiguity of 

term, 20. 
Neutral point, temperature, 88. 
Nystagmus, 99. 

Objects of consciousness, 7; ma- 
terial, 19. 

Occult, the, 342 ff.; and psy- 
chology, 3. 

Olfaction; physical conditions 
of, 19, 50 f., 53, 101. 

Olfactory region, 49 f . 



366 



INDEX 



Organic sensations, 97 f . 

Osmic sensibility, variations in, 

53 f. 
Overtones, 125 ff. 

Pain; as sensation, 86, 90 ff.; as 
feeling, 242 ff. 

Parachromopsia, 68 ff. ; detec- 
tion of, 69. 

Parallax, 223, 226. 

Parallelism, 25. 

Partials, tonal, 125 ff., 132 ff. 

Pathos, 260. 

Perception, 17; and the concept, 
197 ff.; of things, 227 ff.; true 
and false, 201 ff.; causes of 
false, 208 ff. 

Perceptual reflex, 267. 

Personality, alternating, 291; 
multiple, 331 ff. 

Perspective; aerial, 223 f.; an- 
gular, 223, 225; linear, 223, 
224 f. 

Photo-chromatic interval, 65. 

Physics and psychology, 8 f., 11. 

Physiological reflex, 265 ff. 

Pitch of auditory sensation, 81 ff., 
119, 123 ff., 134 f.; and exten- 
sion, 124 f.; and intensity, 135. 

Platonic Idea; and the concept, 
166; and Matter, 150; and re- 
lations, 149. 

Pleasantness, 242. 

Pleasure; as emotion, 262 f.; as 
feeling, 242, 244 ff. 

Present content, 17, 163. 

Present moment ; actual and log- 
ical, 240 f.; specious, 308 ff.; 
logical, 308. 

Process, psychological, 184, 273 f. 

Protensities, comparison of, 121 f. 

Protensity of sensation, 34, 120 ff. ; 
and duration, 233. 

Protopathic sensibility, 93 f . 

Pseudo-mystical experience, 349. 

Psyche, 2. 

Psychic and psychical, 3. 

Psychic research, 3, 342 ff. 

Psychological analysis, problems 
in, 185. 

Psychological moment, 3. 

Psychology, in popular usage, 3; 
definition of, 4 ; preparation for 
study of, 8; and the soul, 2, 341. 

Psycho-physics, 114. 



Psychotherapy, 351 f. 

\l/vxokoyia, 2. 

Qualities; cutaneous and sub- 
cutaneous, 86 ff.; gustatory, 
45; kinaesthetic and ccenaes- 
thetic, 97 ff . ; olfactory, 52 f . ; 
visual, 56 ff.; schematization 
of, 62 ff. 

Quality of sensation, 33; audi- 
tory, 83 ff. 

Rate, temporal, 232, 236 ff. 

Recall, 177 ff.; and fading, 178; 
spontaneous, 177 f.; volun- 
tary, 192 ff. 

Recognition, 175, 239. 

Redintegration, principle of, 
187 ff. 

Reflexes, 265 ff. 

Reinstatement, principle of, 
187 ff. 

Relations; in association, 186 f. ; 
directly experienced, 14, 146 f, 
151; elementary and complex, 
148 f.; in emotions, 262; and 
fusions, 183 f.; imagined, 
165 ff., 222; and logic,151 f.; 
motor theory of, 151; neural 
conditions of, 147 f.; and Pla- 
tonic Ideas, 149 f.; spatial, 
214 ff., 222; temporal, 230; and 
vividness, 300 f., 305; in vol- 
untary recall, 194. 

Relative strength, principle of, 
190 ff. 

Relativity of sensation, 110 f., 
116 f. 

Repugnance, 242 ff., 250 ff., 269 ff. 

Retention, 170 ff . ; conditions of, 
172 ff.; effective without re- 
call, 174; individual variations 
in, 171 f.; and recall, 177; and 
the subconscious, 327, 329. 

Retinal rivalry, 319. 

Retinal streaming, 78 f. 

Rhyme and association, 189. 

Rhythm, 308 ff . ; and association, 
189. 

Rods and cones, 54. 

Saturation, chromatic, 63. 

Scale; chromatic, 130 f.; dia- 
tonic, 125 ff., 128 ff.; equally 
tempered, 131. 



INDEX 



367 



Scales, primitive, 129, 130, 131. 

Secondary phase of sensation, 
306 ff. 

Self, the empirical, 285 ff.; di- 
vided, 289 ff.; function of, 
288 ff. 

Sensation, 14, 43 f.; and algo- 
hedonic tone 244, 250; charac- 
ters of, 32 ff. ; and image, 306 f., 
317; lag of, 27 ff.; localiza- 
tion of, 137 ff.; location of, 23 
ff.; and nervous process, 20 ff., 
25; and stimulus, 18 ff., 27 ff., 
109 ff.; two phases of, 306 f. 

Sensation-continuum, 42 f.; vi- 
sual, 56, 57 ff. 

Sensational reflex, 266 f. 

Sensations: of ache, 91, 100: al- 
getic, 86, 90 f . : auditory, 81 ff. ; 
physical conditions of, 102 f.: 
classification of, 38 f . : coenses- 
thetic, 95, 97 ff.; and emotion, 
259 f.: cutaneous and sub-cu- 
taneous, 86 ff . ; dissociations of, 

94 f.; end organs of, 84 f., 94; 
topography of, 92 f.: of effort, 
97: gustatory, 44 ff. ; physical 
conditions of, 103: of heat, 90, 
93: of itch, 91: kinaesthetic, 

95 ff . : olfactory, 49 ff . ; physical 
conditions of, 53, 101, 103.: of 
pressure, 87 f., 94: secondary, 
31 f.: subjective, 156: tactual, 
86 f., 92 f. : terminology of, 39, 
42: titillatory, 87, 93 f.: tricho- 
aesthetic, 39, 93; visual, 56 ff. ; 
physical conditions of, 101, 
103: of warmth and cold, 88 ff. 

Sense organs, 40 ff. 

Senses, 38 ff. 

Soul, 2, 341; a multivocal term, 
5. 

Sound wave a continuous stimu- 
lus, 31. 

Space; and auditory perception, 
226 f.; and local sign, 122, 139; 
mathematical, 212; and mus- 
cular sensation, 218; three di- 
mensional, 220, 223 ff.; two 
dimensional, 217, 219. 

Space perception, theories oJ, 
212 f. 

Space relations, 213 f., 222. 

Spaces, co-ordination of, 218 ff. 

Span of consciousness, 310. 



Spectrum, chromatic, 56. 

Spinoza's theory of emotion, 259. 

Spinozistic monism, 339. 

Spirits, 353. 

Spiritualism, 350 ff. 

Stimulation, intermittent, 28 ff. 

Subconscious, the, 325 ff. ; and 
hypnotism, 328; misuse of con- 
cept of, 173, 326 ff. 

Talbot-Plateau law, 29. 

Taste buds, 42 ff. 

Telepathy, 343. 

Telephone theory of tone percep- 
tion, the, 82. 

Temperature-zero, 89. 

Temporal extent, 232 f.; meas- 
urement of, 233 f.; direct es- 
timation of, 235 ff. 

Te^minolog5^ principles in, 5. 

Things, metaphysical, 229; per- 
ceived, 227 ff. 

Three color theory, 59 ff. 

Thresholds, 101 ff ; difference, 105, 
114 f.; stimulus, 101 ff.; two 
point, 139 ff., 217. 

Timbre, 83 f., 132 ff.; schematic 
representation of, 133. 

Time; metaphysical, 231, 239; 
passing, 230 ff . ; past and pres- 
ent, 238; and protensity, 121; 
and retention, 172 ff. 

Time order and recall, 189 f. 

Time perception, theories of, 
229. 

Tone: affective, 242 ff.; and neu- 
ral process, 245: algo-hedonic, 
35, 243 ff.; and intensity of 
sensation, schematized, 245 f. ; 
and sensation duration, 246; 
and imagination, 247 f.; and 
repetition, 247; conditions of, 
248 ff . : emotional, 243. 

Tone intervals, 130. 

Traces, mental, 170 f. 

Transcendental unity of apper- 
ception, 339. 

Vedantist theory of the world, 23, 

24, 25. 
Vision, single and double, 141 ff. 
Visual acuity, 55. 
Vividness, 293 ff.; and efficiency 

of thought, 302 f.; factors de- 



33 



/ 



368 



INDEX 



termining, 298 ff . ; fluctuations 
in, 316, 318 ff. ; and habituation, 
314 f.; and intensity, 295 ff.; 
lower limit of, 325 f. 
Volition, 270 ff.; as activity, 
273 f. 



7. */Sr7y3 . 



Wind instruments and the dia- 
tonic scale, 127. 
Wish, 274. 

Young-Helmholtz color theory, 
the, 59 f., 70 f., 73, 79. 



Weber's law. 111 ff. 
White, 67. 



Zwaardemaker's classification of 
odors, 52 f. 



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